Seeing as I'm using a full length surface weir and a tower sump.  The overflow system couldn't be simpler. Effectively,  water flows over the weir and drops into the weir section, where it exits the tank via 2 x 50mm outlets that join to a common overflow pipe that runs across the back of the tank. This then runs to one end, where it then changes direction to flow across and into the overflow compartment of the tower sump assembly. Just prior to this outlet though, there is a tee section with control tap, to take whatever portion of the overflow water I want, direct to the skimmer. In effect, the skimmer is gravity fed directly from the overflow pipe negating the need for a feed pump. This also means that I can tailor flow to the rest of the tower sump including the DSB area to a flow rate I'm happy with. This also means that i can remove the largest portions of waste matter more effectively as they will usually drop down the easiest route (i.e. to the skimmer) rather than going to the main sump assembly. This means less work for the DSB without starving it completely.

Image 1: The main overflow manifold running across the back of the tank taking water from the weir.

Image 2: Tee off before going to the sump, is the feed for the skimmer, controlled by a flow tap. Note that there is a reduction in pipe size halfway down this pipe. This causes any air passing down this pipe to bounce back upwards before going to the skimmer, consequently ensuring the skimmer only receives a stable flow of water. large air bubbles entering the skimmer would disrupt even air flow.

Image 3: The outlet into the main overflow compartment of the tower sump.

image 4: A small ( reverse lit ) refugium area is at one side of this overflow tank to generate the growth of Cheatomorphyllia, and encourage migration of micro diversity throughout the system.

After passing through this first overflow tank which incorporates a lit algae section to one side, water flows over a baffle into a compartment housing two Durso's. which feed to the DSB tank below. Water enters the DSB area via a split baffle so that waste is forced across the surface of the DSB ensuring waste gets a chance to settle out and feed the bed effectively. From here, two more Durso's take water down to the final return tank at the bottom of the tower which fees the return pump, and accepts water returning from both the skimmer and phosphate reactor.

Image 1: Durso set 1 from the main overflow tank.

Image 2: outlets into the DSB section below.

Image 3: Durso set 2, taking water from the DSB, down to the final return compartment.

Image 4: final overflow from the DSB into the return section. (note the angled baffle to disperse bubbles which would otherwise end up being blown back into the main tank via the return pump.

image 5: the main return section. water passes from the right hand side where it runs under the angled baffle, to this section where it passes over a shallow baffle first (on the right of this shot) then under another before making it to the return pump intake (submerged pipe), The pipe nearest is the outflow pipe from the skimmer. and between the two is the auto top up float valve.

If you look closely at the Durso arrangements in the shots above, you will notice that one is set up as standard with a downward facing elbow, but the second has the elbow turned sideways. this enables the second Durso to scavenge from the surface, taking any surface dust with it. As such, there is nowhere in the entire system where a surface film is allowed to gather that may cause pollution or at best, limit gas exchange causing possible pH problems. In fact with 4 Durso's and 2 overflows running, you would expect the system to be quite noisy. This couldn't be further from the truth in fact. Seeing as water has to travel such a short distance between sections, noise is minimal. Additionally, this constant overflow action helps the pH of the system tremendously. As such, in the 4 months the system has been running fully operational, it has maintained a steady pH of between 8.36 and 8.42 almost constantly.

The image below shows the entire tower sump assembly in operation. with the blacked out cryptic tank (top) fed from the main return pump and overflowing directly back to the main tank. Below the cryptic tank we have the overflow tank, then DSB, and finally the bottom return tank.

As a measure of effective space utilisation. This assembly holds over 100 gallons of water in a footprint covering just 24" x 24" leaving the entire underside of the tank free for equipment.

After water has made it to the main return tank (bottom) either by way of the DSB or skimmer, it is then time to get it to the rest of the system. This was done by making a return manifold which will split water pumped from this bottom tank, back to the main tank and other areas. These include both the Cryptic tank, Phosphate reactor, and a spare outlet for adding kit at a later date.

In these shots, you can see the return manifold assembly.

image 1: the main return pump drawing from the main return tank (note the flexible connector which limits vibration and noise) The pipe in front, is the outflow pipe from the skimmer which is situated to the left of this.

Image 2: The entire return assembly including flow taps at all key locations. These are essential for adjustment or shutting a piece of equipment off should there be a problem.

Image 3: Flow is split as follows after travelling up a 40mm pipe from the pump outlet. all feeds from this main manifold are 25mm.

A: return to tank, split (out of shot) into 2 x 25mm nozzles feeding in just below the water surface.

B: Feed for cryptic tank, which feeds water in just above water level.

C: spare feed for future equipment.

D Just out of shot is the feed for the Deltec Phosphate reactor.

The red lines are dirty water from the main weir (split to the skimmer and main overflow tank), and the green line is the overflow from the cryptic tank which feeds directly back to the main tank.

Preventing floods and siphoning:

It wasn't necessary on this set up to drill the return nozzles at the tank to prevent siphoning. Because the feed to the cryptic tank (highest point) is above water level, there is an immediate inrush of air via this pipe as soon as the return pump fails or is switched off. This ensures that the feed to the tank is immediately broken as well, reducing back flow and any possibilities of the tank draining large volumes back to the sump.

The skimmer feed,  and Po4 reactor feed (Pipe with blue tap which runs behind the skimmer feed)  can be seen in these following shots. The return from the phosphate reactor runs strait back to the main return tank.

So with that, we will leave the plumbing there, except to say that you will shortly be able  find details of the solenoid valve controlled Auto Top Up System in the DIY section.

Continue to the next page for more build info.