I think I need more flow? Help, please?

[LynnCeeBee]

I think I've misunderstood a couple of things I've read, and I think I need more flow in my tank. Right now, I have two pumps, rated 500gph and 350gph, coming from my wet/dry filter (minus bioballs!), and a 350Mag canister filter (without any media except for a bag of Purigen.) My tank is a 125g FOWLR (but I am contemplating putting in some mushrooms) with under 20" worth of total fish size. I don't really want to add anything until I figure out the flow problem, though. If I add more flow, how much should I add? Should I add it through up-sizing the wet/dry filter pumps, or through the addition of powerheads like a couple of Hydor Koralias?

[cmor1701d]

Do you have any live rock in the tank?

Generally you want to have 10x-20x water volume of flow in the tank (gph). For a 125 you want 1250 gph or more flowing through the tank.

I would use a couple of Hydor Koralias.

[LynnCeeBee]

Yes, I have about 140lbs in the main tank, and another 30lbs in the wet/dry.

How exactly would I figure out how much flow I have now? I don't understand what "head" means (well, in aquarium speak, anyway!) in terms of subtracting and adding gph according to turns and stuff. I think I got really lost trying to figure out how much more flow (i.e., which Hydor Koralias, and how many.)

Thanks for all your help.

[Kurt_Nelson]

"Head" is just the distance that your pump has to pump water back up, until it reaches the tank. It's probably about 3 feet or so. Once you know this, then you can find a chart that is specific to your pump that tells you what flow you should expect at your tank. The chart accounts for the "head loss" from the additional work the pump needs to do to lift the water.

With that said though, with the 2 sump pumps and the Mag350, you probably have somewhere between 900 and 1000 gph turnover coming into your tank. Roughly. I'd probably supplement that with a couple powerheads rather than by increasing your return pump size. That way you have more control over where you place the flow source and can tuck the powerhead behind rockwork to hide it, or place it to bounce the flow off the sides of the tank, etc. I'd also suggest a couple Koralias, at least the #2, maybe the #3.

[LynnCeeBee]

I never cease to be amazed at the help this forum so freely gives out. Thanks!

I just bought a couple of the #3 Koralias. Last questions: Since they don't have to pump water any distance up, that means that their rating of 850gph does not have to be adjusted? And once I get them into the tank, I would have (roughly) 2600-2700gph to work with? Would it be better just to use one pump, or is more flow better?

[cmor1701d]

MOre is better to a point. Some corals like areas of high flow, some medium and some low. Good luck finding good definitions of those terms <g>. The rockwork will break up the flow and cause it to bounce around which will give your tank areas of greater and lesser flow.

The power heads are calculated at their rated volumes as you surmised, because there is no restriction.

Hope that helps.