Water Flow

Hey, I'm new to the hobby (even though I apparently registered on these forums a long time ago), and had a quick question regarding water flow.

Is a 750 GPH water pump enough for a Fish-Only 75 gallon tank? What about if I decide to try some easier coral in the future? What is the general recommended GPH for fish and coral?

Thanks!

 

By water pump. Do you mean a return pump from the sump underneath? Or a powerhead in the tank moving water?

 

My bad, I mean a powerhead that creates a current in the tank.

 

Righ on, thanks for the clarification, will help when the pros start to comment. Lol I'm no expert but I would want more flow. Also, I'm a big fan(as many people are), of multiple flow sources. Creates a better dynamic in the tank.

 

Thanks for the reply. On a related note, is there a guide out there on the placement of the pumps? I feel like sticking them in at random will be inefficient, but I haven't been able to find any real info on WHERE to put the pumps.

I've only had water in the tank for 2 days now, so I have time to get everything right.

 

I would do no less than 10x tank volume for a fish only tank. 20x-30x is common for coral. Anything higher is usually reserved for SPS dominate tanks.

So, to answer you question. Is 750 enough, very possibly. It really depends on your tank setup. If you have a lot of live rock, or a tank over 3 feet long, two separate powerheads are recommended to achieve better flow. You really want no dead zones in the tank.

 

My 46gallon has a 750gph and 2x 425gph powerheads.
Truth is we should not be measuring gph and suggesting a minimum gph to turn over a tank Xtimes/hr. It helps with an idea but is really more important with filters where you want the tanks water to come into contact with filter media.

With powerheads the goal is to create a nonpredictable constant flow. This is not just to bring food to corals and take waste away from them (although is much more important in these cases) but even in fish only systems to keep all detritus from settling and breaking down into nitrates. Dead spots will make themselves known when cyano outbreaks occur and when you see piles of detritus accumulating. Is one powerhead sufficient for any tank other than a small nano, probably not, I would get a few 750s or even one that does 1000+. Sounds like a lot but it really is not all that strong. As for placement I like to point them either at each other on opposite ends where their currents will bounce off each other and create random water movements, or on the back of the tank at the front glass to bounce the waterflow in multiple directions. When I started I asked these same questions and as much as I hated the advice " Your tank will let you know" and "Just watch your tank" the more I now realize this is the best and truest advice you can receive.

People also say you can never have to much flow. Remember, the amount of flow and the strength of the flow is different! Can you have to much flow? Maybe but probably not! Can your flow be too strong? YES!! Thats why you dont want to buy 1 3000gph powerhead for a tank and call it a day! If you fish are blown against the front glass and pinned you have to much flow. If your corals are bent in half and deteriorating you have to much flow.