Need input on my sump design.

[MrSandman]

Need some input on a proposed sump design for a 90G tank. Below is a photo. Does everyone here think it will work? A friend of mine thought that the last chamber (where the return pump goes) might be too small and will not be able to keep up with the demands of the return pump and end up running it dry. By the way, the mesh looking material is simply eggcrate to keep the macro contained. The macro chamber will only house macro, nothing else. Opinions?

[pjf]

I'm not sure how humid it is where you live but in dry Colorado, I lose a couple of gallons a day to evaporation. My compartments are sized the opposite of yours. The return section is the largest and the skimmer and algae sections are the smallest.

Despite allocating two-thirds of the 29-gallon sump to the return compartment, it will require a refill within a week. Be sure to add a level controller to stop your pump if the water level drops too low.

[SuperAWE]

Your return area volume calcs out to be about 2.3 gallons. That may be a bit low, unless you have an ATO with good reserves.

[MrSandman]

Actually, the return chamber area is 4x10x8 which is about 1.4 gallons. However, if i plan to run the sump at a water level height of approximately 13" deep i'll have that entire volume of water above the level of the last baffle which calculates out to a volume of 24x20x5 where the 5 inches is the total height of 13" minus the height of the last baffle (8") which gives me a total volume of about 10.4 gallons which has to evaporate before the water level drops below the height of the last baffle and the return pump starts sucking air. Is my thinking correct???

By the way i do plan to run an ATO (Auto-topoff system on this tank) but i still want some sort of a buffer zone.

[MrSandman]

Originally posted by pjf
I'm not sure how humid it is where you live but in dry Colorado, I lose a couple of gallons a day to evaporation. My compartments are sized the opposite of yours. The return section is the largest and the skimmer and algae sections are the smallest.

Despite allocating two-thirds of the 29-gallon sump to the return compartment, it will require a refill within a week. Be sure to add a level controller to stop your pump if the water level drops too low.

The weather here isn't as dry as Colorado, but then again isn't as humid as Texas either. Its comfortable, and considering i live about a mile from the Pacific it shouldn't get too bad. On my old 150G tank i would evaporate about a gallon a day on the hottest of days.

Your sump is similar in function to mine. However, if you lowered the wall between the macro and the return chamber and also the wall between the macro and the skimmer chamber several inches, and then used some sort of eggcrate to contain the macro you could raise the operating water level of the sump much more and have an even larger buffer volume before having to top-off, right? Of course this is all taking into account any back-siphoning from the outputs when you shut the pumps off. Unless i'm way off base here.

[pjf]

OK. I see that you have a variable water level in your skimmer & algae compartments, so the water level in those compartments can vary from 14" to 8" in depth. Many skimmers require a specific water level for optimal performance so be careful with your skimmer selection.

Instead of eggcrate, I use a removable mesh screen, such as a "Beta tank divider," to keep algae in place. The screen frame is held against a partition by the water current.

Another reason for a large return compartment is to make water changes easier. I mix my salt solution in my return compartment. Here's another shot with the water level higher:

I also keep the water level in my algae compartment at a constant level. An upward current suspends the algae.

[MrSandman]

Originally posted by pjf
OK. I see that you have a variable water level in your skimmer & algae compartments, so the water level in those compartments can vary from 14" to 8" in depth. Many skimmers require a specific water level for optimal performance so be careful with your skimmer selection.

Good point. Forgot to mention that I'll be running a reef octopus external skimmer in the sump which will be gravity fed by the overflow. so the water level in the skimmer chamber shouldn't have any effect on the skimmer performance at all.

Another reason for this design is that i didn't want any water cascading from one chamber to the next in order to cut down on any waterfall noises. Plus, it also cuts down on microbubbles as well.