SPS and flow
 

So how much flow do you think your SPS tanks needs, and why do you think that?
I've been playing with flow and am questioning the Internet :)

Very good question. I've read many times that for SPS (and really we're talking about acropora/montipora) flow is equally as important as light.

I know I want to add more flow, currently in my DT I have around 32x/hr turnover. I'd like to double that, but my current SPS frags seem to be doing well at the moment.

I often wonder how much flow they need as well.
Tried experimenting in my frag tank and killed all the flow except the returns and they were fine for at least 5 days. It seemed as if that had no effect on the sps. However I haven't tested long term to see what happens.

Without any flow at all. Some sps start to slime up.

Interesting question. Following for sure. I just used EcoTech's flow calculator in regards to which pump I needed... I should be good, right? :noidea:

I have killed sps putting direct flow onto it , so I now keep direct flow away from sps and have the current just pass the piece .

I have used a wp 40 and a wp 20 synced at full speed in my 70 gallon and the corals sure loved it. That's before wp40 died and the wp20 seems to keep the corals happy.

Why I ask is that after adding the Moorish Idol, I noticed he wasn't happy with a million times turnover in the tank. So I've knocked the flow down about 70% and notice that all the movement in the corals (LPS and SPS polyps) remain the same. The food added flows the same, and overall, I can't see how the lower flow would negatively impact the tank. I always baste the rock once a week, and that too is still going down the overflow.

Now, my tank is mostly frags and small colonies. I can see needing to increase flow once I have full colonies, simply because they will diffuse flow. But overall, moving from (up to ) 100x turnover to maybe 30x seems to make little difference.

I'm adding a school of blue eyed cardinals shortly, and I have read that they didn't do well with flow found in typical acro dominated tanks. So I'm just thinking, maybe typical isn't based on anything real??

I do know that increased flow results in thicker and more solid growth. So once I start seeing substantial growth, I will adjust flow up if I notice spindley growth patterns happening.

Just a thought :)

I always thought water velocity and the shape of the water flow / cone / whatever was the more important thing to get right. I've always kind of thought the "must have moar turnover" school of thought was kind of silly in much the same way it was silly to speak in terms of "watts per gallon" 15 years ago when we talked about lighting.

Your plan seems more or less legit to me. FWIW.

I've not decided between 2 options:

(1) The maximum possible flow tolerated by the corals, to basically eliminate the static barrier layer (analagous to insulation) of water around the surface of each coral, to maximize diffusion from the coral to the tank water and vice versa.

(2) Enough flow so that every SPS coral everywhere in the tank gets some flow. Ie. there may be excessive flow in some areas of the tank, to ensure that there are no "dead" areas or areas of low flow.

I am doing option (1) but have had edges of some corals killed when too near a powerhead. I have a feeling option (2) is correct, which is why the Maxspect gyre seems interesting - it would ensure flow everywhere in the tank without excessive flow in any one area.

The other option I thought about was just brief periods of very high flow, such as a minute of high flow every 15 minutes, might experiment with that.

I guess I'm currently sitting at option 2. I just sat in front of the tank and looked at all areas, and all get "sufficient" flow, with some maybe getting too much. It appears that all, even with option 2, have enough flow to break that barrier, if there is a barrier, and it can be broken :)
But all polyps out, all moving well, and sand (mostly) staying on the bottom. I think I can move pumps around a bit, and maybe even lower a bit further. I don't think the cardinals will like it now :)