what size overflow
- Thread starter tolboy
- Start date
scsinet
Active Member
It depends on your tank type and your flow approach.
If you are doing a reef, you want 10 times the tank volume in turnover every hour... so for a 125, you want 1300-1500gph.
If you are planning to try to get all that flow through your main filtration system, you should size your pump and overflow together.
In this case, you need to figure out how high your pump has to lift water (head height), choose the "line" of pump you want, and get one that moves 1300GPH at the height you figured. The actual number will be close to this but not exactly.
Take that actual number, add 20 or more percent, and that's your overflow capacity. You always want to upsize your overflow by 20% or so. They work better when operated at less than full capacity.
If you are doing a FO or FOWLR, you are on your own to figure out how much flow you want, but you can use the above method as a guide to figure it out. Same goes if you are doing a reef but plan to employ powerheads to help supplement your flow.
If you are doing a reef, you want 10 times the tank volume in turnover every hour... so for a 125, you want 1300-1500gph.
If you are planning to try to get all that flow through your main filtration system, you should size your pump and overflow together.
In this case, you need to figure out how high your pump has to lift water (head height), choose the "line" of pump you want, and get one that moves 1300GPH at the height you figured. The actual number will be close to this but not exactly.
Take that actual number, add 20 or more percent, and that's your overflow capacity. You always want to upsize your overflow by 20% or so. They work better when operated at less than full capacity.
If you are doing a FO or FOWLR, you are on your own to figure out how much flow you want, but you can use the above method as a guide to figure it out. Same goes if you are doing a reef but plan to employ powerheads to help supplement your flow.
jessecnc
Member
Unless this is a softie only tank, and even then, 10X turnover is pretty low. I'd shoot for 15X to get started. If you want to mix in LPS go 15-20X, and for SPS figure on 20X+.
Not a good idea in general to run all of it through the sump, so figure on around 1200GPH from the overflow to the sump. Then add additional powerheads or a closed-loop system to make up the rest. By leaving the remainder for powerheads or a C/L, you have the freedom to add as little or as much flow as you want, so the tank can grow as needed and be more flexible when it comes to coral/livestock choices.
As for the sump volume, it does play a role, but you only need around 12gal. capacity to handle 1200GPH. If you take into account backwash, figure on a total of 20gal. to be safe. If your planning on part of the sump being a refugium, that changes things as well.
Not a good idea in general to run all of it through the sump, so figure on around 1200GPH from the overflow to the sump. Then add additional powerheads or a closed-loop system to make up the rest. By leaving the remainder for powerheads or a C/L, you have the freedom to add as little or as much flow as you want, so the tank can grow as needed and be more flexible when it comes to coral/livestock choices.
As for the sump volume, it does play a role, but you only need around 12gal. capacity to handle 1200GPH. If you take into account backwash, figure on a total of 20gal. to be safe. If your planning on part of the sump being a refugium, that changes things as well.
