BASIC CHEMISTRY 1 ON 1.

To fully understand and keep marine organisms its important to first realise and understand what environment we need to maintain, so that we can keep them as healthy and stress free as possible. We therefore need to have a basic knowledge of what goes on 'chemically' in the confines of the closed marine aquarium. to this end I have written this section with the aim of giving the new comer some basic terms and information to go away with. I have devoutly steered clear of chemical symbols and equations as they confuse me and I cant get my keyboard to do all those small numbers after the letters. :-) You will learn from this section an old saying in the marine world. " Don't try to keep the animals, try to keep the water, and the rest will take care of itself"........

1 What is sea water.

Basically sea water is a concoction of over 100 elements ( by this, I mean Calcium, Magnesium, Strontium, etc, etc) held in a liquid suspension of H2O (or plain water). Many of these elements are essential, some are not so, some others we know very little about as to there relative importance to what we 'as hobbyists' are trying to achieve. All of these elements are found in varying concentrations in nature usually measured in ppm (parts per million) or ( 1.03 milligrams / litre). Some are gases, some are metals etc. I will run through some of the more important elements later, however it is impossible to cover what each and every element does for our livestock, and equally impossible for us to test to any degree of accuracy with many of them. We therefore rely on a salt manufacturer to put these into a nice little bucket so that we can mix it with our fresh water and end up with something that 'nearly' resembles what we would find in the ocean, minus the bacteria, plankton, algae etc that is usually present. Under normal circumstances Marine aquarists refer to 'real' seawater, as 'NSW' or 'Natural Sea Water' when talking parameters in the aquarium relative to nature.

So lets start from scratch. Our source water.

Most, 'if not all' domestic supplies of tap water fall way, way short of the standards that our animals are used to in the wild. often with extremely high levels of contaminants such as pesticides, nitrate, nitrite, phosphate and other fertilisers which will cause various algae problems etc not to mention various metals such as copper or gases such as chlorine. In order for our stock to be happy, we need to start with water that is as pure as possible, this means filtering our water prior to mixing it with our chosen brand of salt. The type of filtration used is important, as some methods only remove certain impurities whereas others remove more......very few methods remove 'all' the nasties found coming out of our tap. To this end, I would always recommend using a 3, 4, or 6 stage RO unit with a minimum 5 micron pre-filter and carbon block pre-filter to get rid of about 90% of the nasties, and then through a De-ionising resin chamber after the RO membrane to remove the rest.

This is a typical 3 stage RO unit that couples to your incoming water pipe under the sink, and provides the very high quality water that is essential for long term success with delicate marine organisms, especially SPS. Whilst not entirely essential for a Fish only system. I am an advocate of the idea that where corals and other inverts are at stake, the use of RO/DI is of paramount long-term importance. This unit comes with a flush system for cleaning the membrane, and an optional 'auto shot-off' for linking directly to your evaporation top-up tank should you wish to use it.

This should give extremely good quality water, and with the RO unit before a DI resin pod, should make the resin's lifespan allot longer which can be expensive otherwise. Additionally, Its important that we use a suitable test meter to monitor the units performance over time as maintenance becomes essential. T.D.S (total dissolved solids ) meters are relatively cheap to obtain and can give you valuable information regarding the lifespan of the various filter sections before a new membrane etc is required (on average every 12-18months). I normally connect mine between the RO membrane and the DI chamber to monitor the membranes performance, and the second sensor goes 'after' the DI chamber measuring the final (output) results. With a properly functioning unit, you should get a maximum reading of say 0-10 post  membrane and 0-5 after the DI chamber. (these figures are based on an input quality of 400-500 T.D.S which is a pretty average reading for the South of England. London areas may have input readings in excess of 800 at times. How does T.D.S work?, well simply put, it uses the conductivity of dissolved compounds to get a reading, the higher the level of dissolved substances, the higher the reading, the lower the reading the purer the water is. in essence it measures everything except the H20 content of the water sample. So it becomes pretty clear that on average, there is allot of foreign solid compounds/elements in our water (gases excepted) that ideally we should avoid putting into our tank from day 1. Remember, the less rubbish you put 'into' your tank, the less work the filtration has to do to keep control of it. Probably the most important factor, is that we 'cant' test for everything in our source water with the limited range of tests available to us as hobbyists, so if its not filtered effectively, we have no way of knowing what's going into the tank or its long term effects as it builds up through water changes and top up water.  Now its very rare that I make an open gesture to advertise a company on this site as I may seem biased. In the case of RO units though, I'm going to make an exception. Why, well simply put I was lucky enough to have won my second RO unit in a Photo competition run by Russ at Atlantis Aquatics. The fact that I got the unit free isn't why I'm advertising Russ here, neither did Russ ask me to. The simple fact is, that I was so impressed with the unit over previous models. Three major bonuses feature heavily in my decision to recommend them above other well known suppliers.

1. The unit came with clear pods which makes it allot easier to see when the pre-filers need changing.

2.The pre filter was a 1 micron filter, rather than the 5 micron one which are commonly used. This means that the membrane will last allot longer than other units before it needs changing.

3. All the couplings have safety clips that make it impossible for a pipe to pop off under pressure. which I'm sure you would agree, puts your mind at ease when your away on holiday for two weeks with a hundred gallon/day RO unit plumbed in and under pressure running your auto top-up system.

So being up front about it. Give 'these' guys a call, and you wont be disappointed. Those extra touches, really do make your life easier, and will save you money in the long run.

In My case. I have modified my unit 'a little' and it is now a 'six' stage unit, comprising in order of flow.

5 micron pre filter --- 1 micron pre filter --- GAC carbon filter---Carbon block filter---RO membrane---DI pod.

Measured output TDS is 3ppm post membrane and 0ppm post DI. The Input 'Mains' water is at about 385ppm T.D.S

NB; water conditioners/re-mineralizers are not needed with most good quality salt brands. everything you need, is in the salt at the levels most organisms are happy with. Adding extra minerals 'can' upset salt mixes and your water parameters. Adding re-mineralizers can effectively overdose the mix in many cases leading to excessive imbalances before you even start. Likewise, its important to realise that RO water has no real pH value and comes out at effectively 7.0 or neutral. There is no need to 'add' buffers etc prior to mixing salt with RO water as the water will automatically stabilise to around 8.2-8.4 once all the minerals have been added and dissolved via the salt mix and a good period of mixing..

Ok so I've got my 'food grade' plastic bucket of pure water and my box of salt.....what next?

After we have 'slowly' mixed in our salt, using a power head to stir it, and a good quality 'hydrometer or Refractometer' to measure salinity / specific gravity (basically we are measuring the amount of dissolved salts etc in our water sample) to a reading on average of anywhere between 1.021 for fish only - 1.026 SG for full reef systems 'That's 31-35ppt (parts per thousand) at a temperature of about 76-77f' and we have aerated and circulated it for several hours to stabilise the chemical content. We should have a pretty good sample of nice fresh salt mix that 'just about' duplicates the levels of elements found naturally in sea water. (some salt mixes are better at this than others...personally I use 'Instant Ocean which seems of all brands to have the most consistent quality/batch control'. Now this batch of new water will stay pretty much like this until we add a few organisms. At this point funny things start to happen.

NB. Seeing as there are so many different salts on the market it is inevitable that things can get a little confusing with all the advertising hype that goes with it. The best advice I can give is to try all the better known brands, and go with the one your happiest with. Ignore the advertising. any salt is only as good as the person/method used to mix it. Added to the water too quickly, and it will precipitate out the calcium/ Alk/ and Mg content leading to low or inaccurate readings. Mixed at the wrong temperature, and it will give false specific gravity readings. Likewise, testing too soon after mixing will often give funny readings, especially with cheaper kits. Leave the mix stirring and aerating over night if possible to stabilise before testing any parameters. Please also remember that salinity effects compound levels and doesn't necessarily mean a mix is deficient. As a bench mark for standard reef mixes. always mix to a salinity of 35ppt@76f before testing the various parameters. (see 'Salinity' below for further details).

What's going on with my water quality?

Well simply put, all organisms great or small will have an effect on this chemical concoction we call sea water. By and large this is due to assimilation, excretion, precipitation, or simply long term chemical instability (assimilation is the the take up of various compounds / elements) for the sole purpose of fulfilling an organisms various biological functions including digestion, growth and reproduction. A good example of this, is the take up of Calcium (Ca) by corals, so that they can build their skeletons, and the excretion of ammonia as a waste product of the digestion process. By and large there are only a few elements or compounds we can accurately test for which ill come to shortly, Suffice to say that over time these various elements will become depleted from our water, or levels of undesirable compounds such as Nitrate (No3) and Phosphate (Po4), may build up, and our livestock will struggle to meet their chemical demands, or may be affected by accumulation of undesirable elements/compounds.

 In their natural state, these elements are pretty stable, however some are directly linked to others in a way that depletion or accumulation of one element might lead to an imbalance in another or adverse chemical reaction which can upset our water quality and cause us problems. its therefore necessary to understand the basics of what we should test for, how often, what it means, and above all what we should do about our findings.

Ok throw me the test kit........

Right, lets just hold it there,,,,,firstly a few rules.

1. Don't assume that just because everything 'looks' good, all is well. Nearly all organisms have a degree of adaptability that enables them to survive within a certain range of parameters. Some are more adaptable than others. At the upper and lower ends of these ranges we start to encounter stress, but only at the extremes, which may be along way away from the ideal levels. Reduced growth rates, reduced feeding and disease are all signs of these extremes, but even with good growth rates some parameters might be drifting away from ideal over time and it wont be until things are out of hand that we realise, so if your going to test, do it regularly. It's only fair when considering your animals are relying on you.

2. Don't act rashly to test kit readings, as with most things they can be wrong. so test and test again to be sure  before you act......Like wise, all test kits have a useful lifespan and once outside this are next to useless (bin it, and get a new one before you do anything). There are also good and bad test kits out there, so a simple rule is as follows, 'buy cheap - you get cheap' good test kits are invaluable, bad ones are dangerous. 'IMO' 'Salifert' and 'Merc' are probably the best on the market at the mo in the UK, and I would strongly advise these ones over other cheaper ones. Keeping to 'one' manufacturer has the benefit that all the kits within their range will/should be to the same standard of accuracy, and will therefore give a better overall picture of what is going on inside your tank. NB: Please remember that many test kits 'cannot' be used for both freshwater 'and' saltwater (most Salifert kits for one). So testing your fresh water with a saline test kit will probably give false readings.

3. The end result is only as good as the tools used. Most test kits come with syringes and measuring test-tubes etc that are frequently out on their calibration i.e. one test kit that I wont mention that uses a plastic beaker marked at 5 and 10ml intervals, is actually 0.2ml out at the 5ml line and nearly 0.4ml out at the 10ml line. I would strongly suggest that you try to obtain lab standard plastic test tubes and syringes rather than the supplied ones to increase accuracy when testing. these can be obtained through any laboratory suppliers by the boxful in sterile packaging at a reasonable price, (or via the girlfriend if your lucky enough like me). 'I might add, the Salifert syringes are very good though'.

4. Cleanliness is next to godliness, and this is certainly true about test kits. Always wash out any test tubes, beakers, and syringes after use in clean RO/DI water and then dry and re-seal to keep out contaminants. Likewise always rinse them in your tank water prior to use to get rid of any built up residue, and to prevent dilution of the sample with any drops of RO water still inside from when you stored them.

OK, so I know the rules, what am I testing for?

There are various things you can test for but the following are the main areas we are interested in. I have quoted rough figures although some variance  from these is acceptable / preferred by some keepers.

1. Ph. This is a measure of the waters hydrogen ion concentration,  ideally this should be between 7.8 and 8.4 for most tanks, although some people do run at higher levels there are inherent risks such as 'ammonia' which becomes more toxic with rising pH. IMO a perfect reading to aim for would be around the 8.1-8.4 range over a 24hr period but as stable as possible. i.e. if you can get a drift of less than 0.1 over 24 hours, your doing very very well. A persistently low Ph is indicative of a lack of aeration, under efficient skimming on some systems, a poorly set-up Ca reactor giving out excess C02,, lack of air circulation within the room itself, or inefficient biological filtration causing a build-up of dissolved organics (overfeeding). Large populations of algae can also cause big drops in Ph over night when O2 production stops just like terrestrial plants and C02 is released, in this instance it may be worth considering switching your lighting period over in the sump (if that's where you keep your Macro algae) to a period opposite the main tank lights. Or leave the sump light on 24/7. I do this to stabilise both pH and, to minimise the chances of Macro algae going sexual and crashing. Most pH test kits are woefully open to interpretation where colour charts are concerned. I would always advocate the use of a properly calibrated pH probe or pinpoint monitor as an accurate method of assessment over test kits. (NB: Alkalinity has a stabilising effect on pH, in cases of dramatic 24hr swing or persistently low pH, This should be the first test conducted)

2. Calcium (Ca) This is a measure of the total amount of calcium held in our water in ppm. Ideally this should be around 380-450ppm. Corals, coralline algae, and clams can use a massive amount of Calcium, especially in heavily stocked tanks so its important to keep levels up via the use of either a Kalkwasser 'calcium Hydroxide' (lime-water) drip over night, to help maintain balanced Ph/Alkalinity/Ca (although I'm not a big fan of Kalkwasser much these days), Or my preferred method, a proper Calcium reactor in the case of high demands, or a 'balanced' two part additive in the case of low demand aquariums. not to mention regular water changes. Calcium may be boosted separately of other parameters when required (i.e. if you are out of balance) by the careful use of Kent's Turbo Calcium or Calcium Chloride via a drip. On this page you can find Andy Hipkiss's Calcium additive calculator  (NB A low test kit reading, may also be linked to low salinity) Corals struggle to utilise Ca if levels are below 360ppm, whereas precipitation will occur if levels are pushed much beyond 590ppm. Always maintain NSW levels of 425ppm where possible, and in balance with Alkalinity.

3 Alkalinity (Alk) This is a measure of the waters buffering capacity or its ability to withstand a drop in Ph. (see above) Ideally this should be in balance with the Ca level (see Magnesium) at about 2.9meq/l or 8.0Dkh (carbonate hardness) with a Ca reading of 420-430ppm. Corals and coralline algae also effect/deplete Alkalinity as well as Calcium. In heavily stocked tanks it may be necessary to use a Ca reactor or Kalkwasser drip over night, in lower demand aquariums a balanced 2 part additive or water changes will usually suffice in keeping levels up. Alkalinity buffers or 'sodium bicarbonate' should only be used as a temporary fix though, as the whole Ca, Alk, Mg relation will need looking at if your having problems. If you want to find out what the correct balance is for your Ca/Alk reading. Have a look at this  Balance calculator from Andy Hipkiss's superb website. Simply input your current Alk or Ca reading and then click on which conversion you want, to obtain your result. Remember that Red sea levels are slightly different to NSW (Natural Sea Water) levels where our corals are commonly found. (NB A low test kit reading, may also be linked to low salinity) Many hard corals suffer badly at DKH levels below 7.8 where basal stripping and loss of pigment may be encountered.

4 Magnesium. (Mg) is a key factor in the waters ability to maintain a balanced Ca / Alk level. low readings (below 1100ppm) will contribute to a difficulty in sustaining stable levels of Alk and Ca, which can cause a drop in one or the other. Levels of 1350-1450ppm are ideal. Corals use Mg at a fairly slow rate but this depletion should be the first thing tested for in the event of an imbalance where Ca/Alk is concerned. Usually water changes will suffice in keeping levels up, however heavily stocked systems should be monitored regularly, with a possible small dose of additive when needed.  As above, you will find this calculator provided by Andy Hipkiss very helpful in working out dosages for Magnesium supplements  Magnesium Calculator  (NB A low test kit reading, may also be linked to low salinity)

5  Ammonia (NH3) is a very toxic substance released by fish etc as a by product of the digestion process i.e. faeces and wee, and the constant die off and re-growth  of various organisms found within the confines of our system. Usually this is nearly immediately broken down and converted to Nitrite by various bacteria in/on and around our aquarium as part of the nitrogen cycle. Levels within the aquarium should always be undetectable on most test kits and even on the very best ones it should only be a very small reading below 0.01ppm. higher readings are indicative of an immature or cycling tank, overfeeding, or that something has died causing a build up faster than the filtration system can cope.

6. Nitrite (NO2) Still very harmful. This is the second stage in the nitrogen cycle, and is broken down by more bacteria to less harmful Nitrate. Readings should be undetectable on most test kits i.e. below 0.01ppm. elevated levels are indicative of a semi matured / immature system  or a shortfall in the filtration processes with the aquarium due to a die off or overfeeding.

7 Nitrate (NO3) This is the least harmful of the three, and is the penultimate stage in the nitrogen cycle. (prior to being broken down to harmless nitrogen gas under anaerobic conditions). Nitrate levels should ideally be undetectable, however this can be very hard to achieve in some systems without the use of a DSB, plenum or refugium. levels below 10ppm are acceptable by most corals although this is still very high compared to natural seawater concentrations of around 0.001ppm. It is interesting to note that 'some' No3 is essential to the symbiotic algae present in our corals, and especially clams, which probably explains why it is present in nature as a background level. Persistently high levels are indicative of overfeeding, poor skimming, poor circulation, bad water change routines, or input through improperly filtered top-up or water change water. In these cases the best advice is to work through each scenario until the source is found.

8 Phosphate (PO4) This is a by product of the biological processes in the aquarium and is also found in many foods at high levels, as well as tap water, hence the need for effective pre-filtration of our source water by way of an RO unit. PO4 is also believed to be a major contributor in the outbreak of problem algae. and  seriously restricts the calcification process in stony corals and clams, even at low levels.  Products such as Rowaphos are good at removing this compound, and  levels must be kept below 0.03ppm. By far the best ways to limit Po4 build-up is with use of a fluidised Rowaphos reactor, a sump containing macro algae, skimmer, and effective fresh water filtration. NSW levels of Po4 are around 0.005ppm to 0.01ppm. At extremely low levels, i.e. those below 0.005ppm photosynthesis will be inhibited in corals, and it may cause bleaching in SPS. so it is advised not to 'over-do' Po4 removal by using excessive amounts of phosphate removing medias... A level of between 0.01ppm and 0.015ppm is an ideal range to target.

9 Salinity (SG) This is a measure of the concentration of salts or 'elements' dissolved in our water. Earlier on in this section I mentioned a range of  31 - 35ppt or 1.021 - 1.026 as a good starting point. In real terms though, there is no definitive 'exact' reading for natural sea water. Much depends on location, tides/currents/ temp and so on and so forth. we only use 33ppt/1.024 as a bench mark average, when real life conditions may vary by +/- 5ppt depending on area etc. Why the range?. Well put simply, It depends on what you are keeping in your tank. If its a Fish only, you may want to stick to the lower ranges as fish don't require the high levels of dissolved elements like Calcium that corals need, plus the fact that many pathogens like white spot struggle at lower salinities. If your keeping a full blown reef tank with lots of fast growing SPS corals you may want to go to the higher range. This has a couple of benefits.

1. You will find it easier to maintain a higher level of readily available dissolved elements like Ca/Mg/etc than you would at lower salinities.

2. Your reducing the need for supplemental dosing. (more dissolved elements, means a slower effect on depletion as it is used up). But there is a small price to pay. Saltwater fish expend a lot of energy getting rid of excess salts that they accumulate through constant drinking unlike freshwater fish that have the reverse effect (this is connected with osmosis and the fishes need to balance H20 concentrations within its body tissues) So the net result is that whilst a high salinity is better for corals, its not 'allegedly' so good for the fish. In my experience I would prefer to stick to a 'stable' salinity of 1.024-1.026 for reef tanks. Stability is after all the overriding factor. Rapid, or constant changes in salinity are extremely stressful for all water dwelling organisms. After all, most of our fish are used to levels of 35ppt or 1.026 so It shouldn't really be an issue.

NB: adjusting salinity levels: This should be done very very slowly over several days where the main tank salinity is concerned. Substituting top up fresh-water for salt water at the same salinity as the tank for a short period is a good way to raise levels without stressing the organisms present. Once the required level has been reached, simply switch back to fresh water for top-up.

10. Temperature. The temperature that we maintain a reef tank at, directly corresponds to the way in which our livestock behave. too warm and many corals will suffer, displaying bleaching, or rapid tissue necrosis, too cold and biological function slows down to the degree that the animals and filtration system start to suffer. Hence we need a bit of a compromise. Whilst wild reefs may display temperature swings over the course of a day or months/seasons. It is widely accepted that the best way to maintain a reef tank is to try for a consistent and stable temperature range. the tighter, the better in most cases. Most successful reefs are maintained within the region 75-78f overall twenty four hour period. In many cases this can prove difficult in the presence of powerful Metal Halide lighting, so the use of a digital temperature controller, fans or chillier and suitably powerful heater can be extremely beneficial. SPS corals are supremely sensitive to temperature swings so its strongly advised with systems housing them that temperature control is thought of as a major factor to success, especially in summer months. The most important factor is stability though, over and above the outright temperature.
 

Ok so what do all these readings mean.?

 Well singularly they mean relatively little, however together, they give a fairly good indicator of the condition of your tank and the various biological processes taking place inside it. but only if you test regularly and log your results. the reason I say 'log' is because you can learn an awful lot from looking at readings over several months done on a weekly  or bi-weekly basis. and the way they interact with items such as water changes or a change / adjustment in some form of equipment.

Its all going wrong............ :-(

Ok firstly 'DON'T' panic. if one or more of your readings are out of the recommended range, you can do more damage by changing it suddenly than if you'd left it alone until the next water change........remember that most organisms will become attuned to a given environment within an acceptable range. Any sudden correction can cause more stress than that organism can deal with. The key is to bring things back into line over several days or even a couple of weeks in some cases.  Bringing the parameters back into range depends on the problem, suffice to say that depletion of one or more elements other than Ca or Alk can usually be handled by a suitable additive or water changes. An 'excess' like Po4 can only be handled by water changes or some kind of remover. organic compounds such as NO3 are directly linked to your filtration methods so excess NO3 needs addressing long term with the use of water changes and more diversity in assimilators such as Macro algae (Caulerpa) and better detritus removal via hermits etc. As mentioned before a DSB is an ideal solution to excess NO3 etc as is efficient skimming.

There are a great many products out on the market with suppliers and manufactures both claiming unparalleled success with a products use, and impending doom without it. This is very very rarely the case where separate minor element additives are concerned such as Strontium, Molybdenum, Boron, etc and the multitude of 'all in one' additives etc. One golden rule, is that 'if you cant test for it, and/or it doesn't give a full chemical analysis on the bottle, then don't add it'......advertising companies are dab hands at telling you why you 'NEED' it, they are not so good at telling you what damage 'too much' can do, suffice to say most minor trace elements, are used up quite slowly and are easily replenished with the use of regular small water changes. We rarely if ever need the additions quoted by some manufacturers. Indeed, there is very little in the way of scientific proof of an independent/non commercially biased nature to back up many of the claims made. There are far more amazingly successful 'non' additive based 'stable' reefs out there, than there are additive loaded ones.

As a summery here's my top tips to ensure an easy life with water quality.

1. learn about filtration methods and nutrient removal.

2. In 90% of cases a skimmer is essential for most systems. Scrimp on this, and you will be constantly chasing your tail.

3. Water purification at the start is a major key to success. IE RO/DI.

4. Additives and water conditioners should only be used as needed and determined through testing.

5. A 25% water change per month with good quality salt, is the ideal way to keep your system fresh despite what test kits may tell you. Remember we cant test for all elements so its a good way of balancing out both accumulation and depletion of lesser elements. but it may take time and several changes if things are already a little out of sorts. patience is the key!

I hope this page has been of use to you.