After much prodding and a great many E-mails, I decided to add these pages in an effort to help those of you who may feel intimidated by this subject. and to dispel a few myths and legends along the way.

Firstly. whilst trying to cover these areas, it should be remembered that I am in no way an expert in flow dynamics, although I do have a sound 'self taught' level of knowledge, and an engineering background coving among other things hydraulics which is quite closely related. It is very frequently the case that I end up in arguments (not that I can be bothered) with some aquarists over the most minute piece of detail. I do try to be polite, but when your faced with someone ardently trying to stress that the 'ultimate success' of your system is dependant on the friction losses of a 90degree elbow, over two 45 degree elbows and that loosing 20.lph output from your 3000lph pump is a terrible thing, then I have to say, "get a life you sad Muppet" There are always better, or more efficient ways of doing everything, 'BUT' there comes a point where you have to pull back and say to yourself, Am I spending more time worrying about my figures and and how to squeeze that last 0.01% out of everything, rather than worrying about the job at hand i.e. your animals. They really really, aren't bothered about having 3000lph over 2980lph.... honest.

Secondly, let me just confirm that what were dealing with here is certainly nowhere near as complicated as plumbing your house, nor does it need to be as precise or technical.

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You'll hear various terms banded about, such as flow rate (pretty easy to understand really) friction loss, (not so easy to comprehend), and head loss (another odd one for the uninitiated). So to start, I'll run through each one of these in turn before I start plastering pictures and technical terms about the page and confuse the hell out of you.

1 Flow rate. This is the rate at which, a given amount of fluid travels along a given length of known diameter tubing. Usually measured in Gallons/Litres/ per Hour/Min. Flow rate is effected by several factors i.e. the diameter of the pipe in question, i.e. wider = a higher possible flow rate. Temperature. i.e. the higher the temperature the thinner the fluid will become and more willing it is to negotiate the length of pipe in question. Friction. i.e. depending on how smooth the internal bore is of the pipe in question. Smoother = a higher flow rate, whereas rough edges or joints will restrict flow. And finally, Pressure i.e. the more powerful the source pump is, the better it will be at overcoming the obstacles already mentioned, and a higher flow rate will be achievable.

2 Friction loss. This refers to the amount of friction within a total set of pipes and bends or single length of pipe caused by the inner surface structure of the pipes, and/or the amount of friction generated by changing the direction of travel via a bend etc. We could also add into this, the amount of friction generated by a simple in-line join/coupling. The 'loss' part is the total reduction in flow rate caused by these items, given in mathematical terms.

3. Head loss/pressure. This refers to the total loss/drop in flow rate/output of a given pump due to the height at which it is trying to pump up to, which is caused by the weight of the water in the vertical pipe trying to come back down under the force of gravity.

Ok, so lets put all that in simple mathematical terms. ( I like simple,,,,)

We are going to take a 1000 ltr/hr pump and draw water from our sump up to the tank, which is 1 metre from the pump to the top of the tank To do this we need the following :

1 metre of tubing that is 1" dia, to match the 1" outlet nozzle on the pump.

And 2x90 degree elbows to negotiate the top lip of the tank.

Now we already have a known figure i.e. the 1000lph output of the pump. What we are trying to find out is how much of this flow we will loose by the time it gets to the other end of our little bit of plumbing, due to the friction of the pipe in question, the loss caused by the elbows and finally the height that we are trying to pump up to. So to make things easier lets just use simple figures as an example.

1. Our pump manufacturer has given us a figure of 1000plh with a maximum head of two metres. What they are actually saying, is that from the output nozzle i.e. zero head you will get 1000 ltrs/hr, but at 2metres you will get 0 ltrs/hr because this particular pump will only pump water up to this height before it runs out of guts. So in effect we now know, that at half this height i.e. 1metre, we can reasonably expect an output of half the max 'zero' output.

i.e.. 1000 / 2 = 500     so that's a total output of 500 lph at 1 metre head.       simple.

Important note. Due to the design of some pumps a linear drop in output may not be the norm. Some pumps suffer no significant drop in output over the first half of their maximum head height but a big drop off in the second half so experimentation may be required. It is also the case that some pump manufacturers will air on the side of caution where advertising is concerned and deliberately under-state the possible output of a pump to cover differences in manufacturing standards from batch to batch. In this respect it is quite common that you will see allot more output than you had originally estimated. This is a good thing at least.. Especially in the case of the pumps I am using which the manufacturer has quoted a max head height of 2.4m, when in actual fact, (after testing) they will quite easily cope up to 3.5m.

Our next job is to find out what effect the hose, and the bends have on our output. For this we need to know the specifics of what 'type' of hose/pipe we are using for working out its 'flow dynamics' or friction loss, and the specifics of the bends i.e. their diameter/bore and radius i.e. how gentle/tight the bend is. By using one of the many flow calculators available, like this one. Click here  We can find out what effect each or cumulative sections have on the overall flow from start to finish. So lets say for the sake of argument, that our strait pipe has a friction  factor of .025/metre and our bend has a friction factor of 1.5 remembering that we have two. this gives us a total loss of 3.25 that's 3.25% of our overall flow.

ie. 1000 - 3.25% = 969.75 or 969.75 lph, minus our original head loss of 500lph

This gives us a total of 469.75 lph output

The end result of all our working out, is that we now know we need allot more powerful pump than we would think, if we want to overcome friction and head losses. In this case, simply by placing the pump at half its 'maximum head' height and then adding a couple of bends, we have effectively halved the output of this pump at the tank end.

Whilst this may seem extreme, I shouldn't panic too much. In effect, simply by ensuring we have a pump with enough grunt to get the water up to the tank with a minimal amount of loss will negate allot of the worry. Bends in pipe work, do have a negative effect on flow rates, but generally nothing in comparison to the difference that head pressure makes (within reason). Obviously having as few bends as possible will make life allot easier for the pump in question, also using pipe that is matched or slightly bigger in internal bore than the diameter of the output nozzle on the pump itself will also help allot. Sticking to the following simple rules will go along way towards ensuring you get the most out of your plumbing, and pump, in whichever form it takes.

1. Having a 1000lph pump that has a maximum head of 4 metre's is better than using a 2000lph pump that only has a maximum head of 1.5 metre's when trying to pump from your sump to your tank that has a top lip of 1 metre from the floor. This is the single biggest factor in what you are trying to achieve. You can always turn an 'oversized' pump down using a flow tap, but you cant boost a wimpy pump.

2. Keeping pipe lengths to a minimum will cut down on friction loss over the entire length of the plumbing in question.

3. Matching pipe diameter to your pump output nozzle is important so that flow is not restricted ie 1" pipe to 1" output nozzle. Equally, too wider pipe may restrict flow when pumping upwards, due to the increasing weight of water held in the pipe in comparison to the output pressure of the pump itself. If increases in diameter are called for, they should only be small increases. (See diagram below) A&B. The volume of water in pipe 'A' will be significantly heavier than he weight of water in pipe 'B'. To this end, Pipe 'A' will have a more serious effect on pump output per vertical meter than pipe 'B' due to increased back pressure, especially if your pump only has a 1" outlet nozzle. In pipes 'C' & 'D' the opposite applies, i.e. pipe 'C' will be more efficient and less restrictive for the pump than pipe 'D' as there is no weight involved when pumping horizontally, however velocity will be lost. Pipe 'D' will be more restrictive due to its smaller diameter however velocity will be increased.

4. Keep bends and elbows to a minimum to reduce friction losses and keep joints as smooth as possible, it is equally important to keep to a realistic radius in relation to bore size. Some pipe manufacturers design bends that are in effect right angles (with corners) rather than a proper 'radius' bend. These will severely hamper flow. (See diagram below) E & F (in 'F' we can see the eddies caused by the sharp angle of the bend.)

Opinions and variations.

Quote." Using 2 x 45deg bends over 1 x 90deg will increase flow"

Well not necessarily, although I can see the logic behind this comment. Remember though, that whenever you add a link, joint, or coupling, you also add another couple of seams that water has to flow over. These internal seams or joints cause a disruption in the smooth flow that we had down the strait length of pipe and restrict or slow this flow. Replacing one joint and its accompanying seams, with two more of a slightly softer radius basically cancels out this benefit IMO. As long as the 90 deg bend is of a gentle radius then I see no real benefit in exchanging it for two 45deg bends.

Quote. " Using soft tubing with big bends instead of elbows increases flow rate and reduces friction"

Likewise I can see where this comment comes from, but in real terms IMO this is the same 'over thinking' as before. One big drawback with soft tubing when it is warm and used for curves, is that it can collapse at the bend centre and kink. This will cause an even bigger reduction in flow, and possible damage to the pump if left unchecked. In severe cases it is feasible that you could effectively shut your sump off all together if a kink developed in your soft plumbing. To this end, I feel the cosmetics and safety aspects of a single hard plumbed bend, out way the risks or possible benefits of the soft tube bend.

         "Fitting wider diameter pipe will increase flow rates" (this is in relation to returns i.e. from pump to tank)

Yet again it is easy to assume this, but in reality all we are doing is increasing or decreasing the speed at which the water is flowing along the pipe. To a certain extent this comment is true, as we are also altering the amount of work our pump has to do to get this water along the pipe as well. To put it in simple terms. As we all know, the laws of physics state that a fluid cannot be compressed. To this end, all we are doing by going up in diameter is increasing the available volume for the amount of fluid we are trying to pump. If we try pumping 1000 ltrs/hr down a two inch pipe it will travel at near enough twice the velocity than if we were trying to pump the same volume of water at the same rate down a four inch pipe allowing for friction losses etc. We will still get 1000ltrs in 1 hour which is controlled by the output quota of our pump. it will just come out the other end at a slower velocity. The only difference the wider pipe plays, is in the work the pump has to do. If we go to extremes and look at the hydraulics industry, we see situations were several litres of hydraulic fluid are needed to be passed down a 10mm diameter pipe within a fraction of second in order to activate a fast action ram. In this case it isn't the pipe diameter that is important. Its the power of the accumulator or pump that is at the other end that's the deciding factor. Effectively the accumulator is able to store a massive amount of energy in the realms of 30-40 thousand psi, and then release this 'in one go' which forces all the fluid down this narrow pipe at amazing velocity to extend the ram at the other end. Fitting a wider pipe has no effect on the speed at which the ram opens the other end, it is purely determined by the power of the accumulator and how fast it can push this fluid down the pipe in question to fill the body of the ram, and extend it.

If we take a look at 'our' plumbing. We are in effect, trying to balance out the work the pump has to do, i.e. too much, caused by too many restrictions or bad/narrow plumbing, will reduce its output. And having a decent amount of output at the other end of the chain so to speak i.e. the outlet / return nozzle in the tank. If we make the piping too wide we decrease velocity of the outlet nozzle, whilst if we decrease the pipe diameter, we will increase velocity but loose force or volume/hr, due to increased backpressure on the pump itself. Cheap power heads are a good example of this, whereby a tapered or narrow nozzle, is used to create the impression of better output. the result of this is a very strong immediate/ local flow that lacks the force to carry any distance. (see diagram below) The output of a circulation pump using a wider nozzle is to give a slower velocity but more forceful flow. So to conclude, IMO it is more beneficial to match your plumbing to the output nozzle of your pump than it is to increase the diameter with a possible resultant loss in velocity. i.e. if your output nozzle is 1", then if at all possible stick to 1" plumbing throughout, but if you must increase , then only go 'up' a very small amount. Never go 'down' in diameter, or use narrow outlet nozzles that give a sharp flow. If we are talking about overflows than yes this comment is correct. i.e. fitting wider diameter pipe 'will' increase flow rate. Under these circumstances we are dealing with gravity flow which doesn't cope very well at all with narrow pipes.

Flow pattern from differing nozzles.

To put the above drawing and words into perspective. Try and imagine the type of flow that corals receive out on the real reef. This flow is strong but well dispersed rather than the type of flow given via a narrow nozzle which is sharply focused. In effect our ideal scenario would be to shift the entire water volume of your tank several feet from right to left and back again every few seconds with your corals staying in the same position. Not feasible really. But we can aim to give a similar flow via the use of powerful pumps linked to wide outputs that give a strong but well dispersed flow.

Outlets and returns, weirs and closed loops,,,,,,what's this all about then?

Outlets/overflows. This is where we allow water to flow out of our aquarium and down to our sump, or pump in the case of closed loops (I'll get to these soon) under the force of gravity. When setting up overflows, its crucial to remember that water flows allot slower under the force of gravity than it does coming back up to your tank from your sump via a return pump. To this end I would always recommend a minimum of twice the diameter tubing for overflows in relation to return pipe. This is just to be on the safe side. Obviously this does not apply to closed loops as they are effectively a 'sealed' circuit. i.e. the rate of suction is equal to the amount of expulsion.

Returns. This is where we 'pump' under pressure back up to the tank via a nozzle or bulkhead fitting running through the back pane, or over the top lip of the tank.

Weirs. These are in effect, walls or dams designed to set the height of water in our tank or sump so that it remains constant despite variations due to evaporation/leakage in other parts of our system. Various methods are employed in this respect from simple surface weirs ( See DIY) to more advanced corner/centre weirs utilising a stand pipe or Durso. Water flows over the top of the weir which is set at your desired water height, and then down to fill the space behind, it then spills over the top of a return pipe or stand pipe which runs to your sump.

Closed loops. This is where we take water out of the tank and feed it through a pump situated below/above or level with the tank and then strait back to the tank again with the aim of increasing circulation without the unsightliness of powerheads. the benefits are that there is effectively no head pressure to overcome as the weight/pressure of water flowing down the outlet is equal to the weight of water flowing back up under pressure. In this case we can use a single pump to deliver high volumes of flow through a number of outlets without any major loss of flow which would be inherent if we were to break the siphon effect by passing the out flowing water through a sump. One easy way to understand the 'no head loss' principle when we talk about closed loops is to look at a see-saw-.'If I was to place a 50kg weight on one end, and then I asked you to push down on your end, you would feel a given amount of resistance. This is what your pump feels when it is trying to pump a 'weight' of water up to your tank, the more water there is i.e. height, the heavier the load will be, and the harder the pump has to work to shift it. now if I was to put 50kg on your end of the see-saw as well, then you would find that it was very easy to make the see-saw move'. effectively we have balanced the weight. This is exactly what is happening in a closed loop, whereby the weight of water coming 'down' to the pump, equals the weight of water being pushed upwards back to your tank. Remember that shut off taps must be fitted to both sides of the pump on closed loops to enable removal and serving of the pump should it fail or leak.

Bulkhead fittings. This is a type of fitting that enables us to attach a section of pipe through a pre-drilled hole in a pane of glass i.e. your back panel or sump. The fitting has a washer on each side which sandwiches the panel between to give a water tight seal, and a screw ring is tightened up to the washers to seal them. It is advised that you loose the rubber washers and simply silicone the fittings directly to the glass panel doing the lock nut up 'hand' tight. Rubber perishes in salt water and bulkhead fittings can come loose otherwise..

Pushfit. This is a type of fitting used to connect sections of piping together. This is a very easy method to work in that allows flexibility. Each coupling (be it strait, or angled) consists of a sleeve into which an 'O-ring' seal is fitted. after cutting your pipe to length you simply 'push' the pipe end into the fitting where the O-rings form a tight seal. There have been concerns about the lifespan of the seals when in contact with sea water, however after speaking to various users, none have reported any problems. One other benefit is that any section of piping may be split for cleaning easily despite any bends present. IMO this problem is also negated by the fact that over a suitable time, all internal faces will effectively be sealed via the bacterial film that builds up on the inner surfaces of the pipe and seals anyway. The biggest thing to remember is that push-fit piping must 'not' be  used, where any form of pressure is involved. It is therefore ok to us it for things like overflow pipes etc, but certainly not for pump returns etc where solvent weld or screw fittings must be the order of the day.

Solvent weld. This type is designed for pressurised fittings i.e. returns or especially closed loops etc, however it will do just as well for non-pressure pipes. Simply put, the pipe sections including elbows etc just slot together as a tight fitting and a solvent is applied to the join prior, to 'weld' the joint together. This is probably the most common type of fitting used. dependant on your preference, you can use budget Marley solvent weld pipe, or the more dedicated VDL pipe in ABS.

Soft link. All pumps, 'to some degree or another' vibrate. If we connect any length of solid piping to this pump, the vibration is transmitted along the pipe and can get quite annoying. A soft link is simply a short section of 'flexible' tubing that is fitted between the pump inlet and outlet nozzle, and the start of the hard piping to soak up this vibration and keep things quiet. (This is usually where any shut off taps are fitted).

Stand pipes. This is a vertical pipe that comes up through the tank base behind a weir. Water flows over the weir to fill the space behind and rises up until it meets the top of the stand pipe, and then overflows down the pipe to our sump below. There are several different methods involved in this set-up, some better than others. The one most common flaw with this item, is a tendency for the pipe to emit an annoying 'gargling' noise as water rushes down it. This is usually caused by the pipe trying to balance itself out between water falling down and air rushing up. Richard Durso's site covers this subject in detail, with various methods of combating this problem. (look in 'Links')

Spray Bars. This is a piece of tube that has numerous holes drilled along its length in an effort to concentrate the outflow of water in the form of several strong jets. These are most commonly used at the back of the tank along the base, in an effort to move waste out from under rockwork, to the front of the tank. This also prevents stagnant areas of flow as well when used under reef structures and the like. The important thing to remember when designing spray bars is to allow enough holes so the output of the attached pump is not compromised, but not too many that the jets become weakened through dispersion. Likewise the holes that are drilled should not be so small that they will easily become clogged with calcareous algae growth and need constant maintenance.

Materials.

Now there's allot of controversy over this subject, and I suppose there always will be. Unfortunately one of the most common flaws with this hobby is that we all come across the odd problem that completely perplexes us. It is very easy at these times to jump to conclusions based on hearsay, just because we have exhausted all other 'apparent' options. None more so than plumbing materials, which by definition give most people a headache. Let me just stress before I go any further, that unless you are 100% confidant in your knowledge of closed system marine biology or knowledge of the various forms of plastics and there chemical make-up then stick to dealer authorised and recommended plumbing materials. I have forgotten how many conversations I've had on this subject over the years, and it always boils down to the same answer. 'Unless you know for certain or have witnessed it with your own eyes that its ok to use, then don't touch it'. There is one argument to say that the dealer will inevitably steer you clear of the cheaper stuff and try to sell you 'approved' aquatic tubing and fittings because he wants your money. There is also the argument that just because it has a picture of a fish on it, means that he can charge you twice as much as exactly the same material sold down the road at the local DIY store without the fish on it?. My only answer to this is you take your chances and pays your money, whichever way you go. On this system, I was using standard hobby pumps so could get away with the cheaper, 'Marley' piping, whereas on the new system, I will be using 'Sequence' 10000lph  high pressure pumps, that require more robust, dedicated aquatic pipe and fittings from VDL.

MARLEY PLUMBING THE 200 GALLON REEF.

For the sake of argument and to protect against catastrophe for those less well informed its quite simple. All materials used in plumbing your system must be either 'potable' or drinking water quality, or 'food grade' i.e. approved for use in the food industry as safe and non toxic. For those wishing for a cheaper alternative, the only type of piping I am willing to say is ok is the 'Marley' push-fit and solvent weld waste pipe that is available through DIY stores such as B&Q. This is the only make of tubing I, and some of my fellow reefers have had experience with, without any adverse side effects. This pipe is available in three sizes i.e. 40mm, 32mm, and 21.5mm. Both 40mm and 32mm are available in solvent weld, and push-fit. however 21.5mm is only available in solvent weld. All sizes come with all the commonly used fittings i.e. bends both 45deg and 90deg, bulkhead fittings, joints, converters, 'T' pieces etc etc. So there really is no limit to what you can achieve. The chemical makeup of 'Marley' waste pipe, means that it is chemically inactive / stable, up to a temperature of 86deg C so in this respect there are no concerns. Rumours of additional anti-fungicide are unfounded I might add, although I cannot vouch for equivalent pipe from other manufacturers. As a price comparison ill run through a list of the fittings and pipes I used on my old set-up, in comparison to the approved alternative as sold through a major UK aquatic supplier in the nearest equivalent sizes and fittings in VDL.

These are total figures including surplus i.e. the bits and bobs left over after cutting the piping to the various lengths I needed. The total plumbing system and instructions can be seen on the next page, however what this list basically consists of, is everything required to plumb up, a 6 x 2 x 2 system comprising of :-

2 x returns, 2 x overflows, 5 x closed loops (using hobby pumps) , and the feeds for skimmer and return pumps.

The total bill for all the above materials came to £ 67.89 through the B&Q warehouse, (prices vary slightly according to region). The equivalent materials as sold through a leading UK distributor in 'potable' ABS/VDL came to £ 236.45 and that's with some discount. To be fair though, you 'should' expect to pay that little bit extra for ABS as it is more expensive to produce especially in food grade. however whether that means warranting a price hike of 4 x is entirely up to the individual to decide. sometimes its better to pay extra for piece of mind if your not sure. So in this respect I'm not going to condemn anybody unduly, whichever way you go. The simple answer is that for smaller tanks, In my opinion, Marley is quite sufficient. For larger tanks (over 200 gall) I'd move up to solvent weld pressure rated fittings and pipe from the likes of VDL to take account of the heavier loads, pressures and strains applicable with larger pro-pumps etc.

Continue to page 2 for photo's and details on construction of Marley plumbing.

Click here

Heavy Duty plumbing, as used on the new 400 gall system.

Coming soon