Too much water flow

[jdizzle1000]

How much water flow is too much for a 20 gallon reef tank?
I have:
- swivelling powerhead 145gph
- small powerhead 90gph
- protein skimmer about 250gph
- hang-on refugium about 200-250 gph
- small power filter 100gph

That is alot of water flow, but most of it is only at the top of the tank... Give me your opinion.

Also, how much light is too much light? I have 150watt metal halide and 65watt actinic PC on during the day. Too much for a 20 gallon?

Thanks.

 

[mysis]

Well people say you can never have to much water movement in a reef tank, That is what your going for right??? I think that the lighting is good, you wouldn't want to go for anything more than that, but MH that size would do fine on a 40 gallon, you could reduce the watts to a hundred if you want to save money. What corals are you wanting to keep??

 

[jdizzle1000]

I want to keep SPS and LPS corals. I just wanted to know if that is too much light, I don't want to deep fry the corals...

As for the water flow, I keep 1 damsel and 1 Percula Clownfish, which seem to be able to swim fine with the current, although they do have to fight against it sometimes...

 

[mogurnda]

I want to keep SPS and LPS corals. I just wanted to know if that is too much light, I don't want to deep fry the corals...

As for the water flow, I keep 1 damsel and 1 Percula Clownfish, which seem to be able to swim fine with the current, although they do have to fight against it sometimes...

The lighting and current are fine. Acropora corals will be very happy with that much light and current, and others will grow quite well. You will want to place LPS corals in areas with somewhat less flow.

 

[Crown Royal]

Not all flow is alike.

You're going to get far more current and flow out of your powerheads than say your refugium or skimmer because of the nature of the flow and how it's directed.

The majority of the flow will come from the powerheads which I'm assuming are pointed at each other. The flow numbers from the other pumps are somewhat misleading because the are far less directional - pretty much gently cascading water downwards. As a result, while you may be turning over about 850 gph, the majority of the current generated (what's important in a reef tank) will be in the form of the 245 gph from the powerheads.

As an example, in my 46 gallon I've got

1. 2x modified Maxijet 1200s = 590+ gph
2. Mag5 on AquaC Remora = 500 gph
3. Filstar XP2 Canister = 300 gph
4. AC500 refugium (cut-down impeller) = 300 gph (est.)

That's around 1,700 gph total and I still just managed to get rid of some cyano algae (a sign of not enough flow to an area) after modding my Maxijets despite being quite a bit more than the usual recommended 10x-20x/hour. This is because it's the Maxijets that provide the majority of the current. Simply putting my hand in the tank or watching my 2-part additive dissolving in the current confirms this.

So if you are looking at SPS, you can clearly go with more flow in the form of bigger powerheads. You can always shield your LPS from the flow by hiding them in the live rock or finding areas of lower flow (usually in the bottom corners).