Too much flow and surface agitation?

[DrBoxedWine]

I have a 75g reef that's in the early stages and i'm wondering if i'm creating too much of a current in the tank. I have 2 Hydor Koralia 750s and the return from my sump is probably in the 500 gph range. The Hydors are a couple years old, and i doubt they actually produce at 750 gph anymore. Maybe more like 600? I don't know this for certain, i just suspect cheaper circulator fans lose some of their power over time. The 2 koralias are near the top of the tank creating some surface agitation. I do get a bit of a strobe effect from my new pair of Hydras that's a little intense, and i'm wondering how much surface agitation you really need.

So, my questions... Is a combined 1800 gph between the powerheads and the return pump too much? I know the general rule of 10x, but that just seems really low to me? I could be totally off here tho and maybe that's what i should really be shooting for. And how much surface agitation do you guys aim for? Any tips or rules of thumb that i should be going for?

Thanks in advance!

 

[bemerritt]

What kind of tank are you shooting for. A lot of sps tanks can get around 30-40x

 

[AdamNC]

I'm running 1,900gph+ in my 29gal and I feel I need another WP-10 for more erratic flow. 1 WP-10 running at max flow of 1,000gph on else, 1 Aqueon 500, 1 AquaClear 70 set up as a refuge on low flow and a Maxi-Jet 1200 on the skimmer.

 

[Crooked Reef]

I'm higher than that. I have a return pump putting about 600gph back in, a koralia 750, 850, 240 and a 425 I believe. The two smaller ones hit the surface from the back and create flow down the front glass. The two bigger ones cut across the back a little below mid level and the return is branched off in another direction. Depending on your rock set up you could be perfect or too much or even have dead spots and not enough.

 

[BlindZide]

As stated above flow will depend on your rockscape, position of powerheads/return, and what you are keeping. You will need to figure out what you are going to keep and build off that.

 

[shesacharmer]

I put two Koralia 1500's in my 75 when I first started and I have 900 gph return pump and I thought it was way too much. I had trouble keeping the sand where I wanted it. When I added more rock, fish,and corals I began to feel I didn't have enough flow anymore and added two 240 Koralia's to the front of the tank opposing one another just to ensure there was plenty of flow along the sand in the front. I think what you might be experiencing is just the newness of it all and as your tank progresses you will find yourself making lots and lots of changes along the way. Best of luck for a successful tank!

 

[thegrun]

I would put your flow on the very low end of what is acceptable for a fish only system and too low for even soft corals. For your tank soft corals would require 2250 GPH, SPS and other high flow corals 3000 GPH minimum.

 

[uncleL]

Depending on how you have your tank setup will determine how much flow you will need in your tank. A good example is on YouTube My very simple 75G saltwater tank.

 

[ViktorVaughn]

I get about 1800 gph in my 40 breeder from my 2 mp10's and return pump. At first I thought it might be too much because even my zoanthids on the sandbed get blown around quite a bit but they seem to like the flow. No closed polyps and growth seems to have picked up from when I increased my flow from 1000 gph up to my current level. Up top where the flow is way higher is where most of my SPS are and they really like the turbulent flow. The mp10s give me a ton of surface agitation too, a small maybe 1/4"-1/2" wave is always present and keeps the surface film I used to always have with low flow and little surface agitation in check.

 

[ca1ore]

Is a combined 1800 gph between the powerheads and the return pump too much?

Nooop! Ought to be just fine. Just keep coral out of the immediate direct stream and you'll be good. Also, if you have an adequate overflow, direct surface agitation isn't necessary.

 

[DrBoxedWine]

Nooop! Ought to be just fine. Just keep coral out of the immediate direct stream and you'll be good. Also, if you have an adequate overflow, direct surface agitation isn't necessary.

How much surface agitation is needed? I have a ton right now in case the return pump ever goes down, but I've thought about just one Koralia in the back near the top pointing straight toward the front . This would provide some surface agitation evenly to both sides of the tank, but not a ton like I have now.

 

[BlindZide]

You don't need a ton of surface agitation, just enough to make it stir the pot.

 

[DrBoxedWine]

Are we looking for just enough that a film doesn't form?

 

[BlindZide]

Yeah, just enough to keep the top clear and to allow for oxygen exchange.

 

[whosurcaddie]

I dont think 1800 GPH is enough for your tank. Thats only 25x turnover per hour. I would shoot for 40.

 

[Crooked Reef]

If you have LEDs and I am sure metal halides you get more shimmer with more surface agitation.