How much water movement is ideal?

narkfish

narkfish

Member
I have a 75 gallon tank, how many gph should I have? There is one 1400gph koralia already in there with a return pump that I don't know exactly how much is giving off. I have another 1400gph koralia that I have but don't want to put in for fear of to much flow. Suggestions? Thanks for any advice.
 
S

saxman

Guest
Different style tanks (reef, FO, SH, etc.) all have their own flow requirements, and the specific inhabitants will also dictate the amount of flow needed/tolerated. Is your tank a reef or FO?
What you're generally looking for (without taking any special inhabitants into account) is some water movement thruout the tank with no "dead spots", which can cause cyano outbreaks or detritus/uneaten food to build up. The other thing you want is sufficient surface turbulence to promote efficient gas exchange.
I know you have a Korallia, but what is your return pump (make/model or gph rating) and how is the water returned? Is the flow split between two (or more) returns? Are you using flares, nozzles, eductors, spray bars? Does your return pump have to pump a long way? Do you have a lot of 90* angles in the plumbing? Other equipment being driven by the main pump (chiller, UV, reactor)?
I know this is kind of a generalization with no specific answer, but the more you tell us, the better we can help you out.
 
narkfish

narkfish

Member
The return pump is a viaaqua 3600 and rated between 800-1000 gph. I have it split between two return lines and I don't have any special nozzels or anything. There aren't very many angles for it to go through just the tee off in the pvc and a 90 on each line. So what do you think?
 
slice

slice

Active Member
The eternal question: do I have enough flow?
I asked this question many times and in many ways and got the same answer: you need more than too little and less than too much. Then I tried to get an answer to: when a piece of debris flows by, should it go t h i s f a s t or thisfast? No actionable answer came.
I have a column tank with tall rockwork, so I have a different set of variables than you, but I can tell you that turnover and flow are different critters. At one point I had 65x turnover but sucky flow. I struggled with placement of 3 koralias to get sufficient flow to no avail. Drove me crazy. My 2 MP10s now gives me great flow throughout all depths and gives good surface agitation.
Saxman gave you the thumbs up for a baseline to work from, but adequate flow, depending on your unique set of variables can only be based on personal observation of your tank bounced off continued research. You will figure it out.
In short, you need more than too little and less than too much.
 
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