SPS and flow

[Tn23]

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.

[WarDog]

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

[Chemicalguy]

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 .

[mrhasan]

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.

[Aquattro]

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

[Delphinus]

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.

[kien]

Originally Posted by Delphinus

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'm totally with Tony on this one and that has been my experience over the past 5 years. When I started the tank I was told to get as much flow in there as possible. So to start with I got two Tunze 6105s to blast the tank with flow with the intention to add more soon after (they're expensive buggers). Well, I never did end up getting any more beyond the original two 6105s.

When I first set up my 6105s I had the both on full blast to get the most out of them. A few months later I decided to play around with varying their speed and programming them with my controller. I ended up with a variable speed setup where one 6105 would run at 100% while the other one ramped down to only 10% flow, and they alternated this way back and forth. This generated some nice random swirly flow and things thrived for the first couple of years with this setup. As a result of this setup though, one tunze ended up not running at 100% at any given time so I effectively had cut my flow rate down from when they were both on at 100%. Anyway, things did just fine.

Early last year the programming cable on my powerheads died so I lost control of them from my profilux. I ended up having to run them both at 100%. I intended to replace the controller cable but never did. The only real change I noticed was that corals were growing in a certain direction (with the more directional flow). Also, corals that were closer to the powerheads were not as happy (less polyp extension). Then in the summer one of my tunzes completely died so I run on one 6105 all summer and fall. The result of this was a gyre whipping around my tank in one direction. I didn't really notice much of a change in the corals that I could attribute to the reduced flow (I had other bigger issues like a busted skimmer).

Anyway, so a couple of months ago I finally got around to redoing my flow by removing the one remaining 6105 and replacing it with toe jebao RW-8s. Each one having significant less flow than the 6105 (on paper anyway). I run these on a pulsating mode to simulate a gentle wave. What I've noticed with this flow pattern is that virtually everything has nice polyp extension (when they weren't being nipped on by my small angels) and seems to be quite happy. LPS, SPS, softies. I haven't seen my corals this healthy and happy since the earlier days of when I ran a more random flow pattern through the tank. This despite the fact that I'm currently running the lowest flow rate that I have ever ran through he tank.

So in 150g, I'm running two RW-8s that are in the magnitude of 2000gph each (but the don't run continuous, they pulse so I don't know what that means to the actual flow rate). Plus my mag 18 return pump which adds a little bit of flow. That gives you an idea of my flowrate.

[trilinearmipmap]

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.

[Aquattro]

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

[Myka]

In my experience, you can have lower flow with frags (like 30-50x turnover), but if there is a point where the corals are impeding the flow then you need big flow just to keep the water column moving. It depends a lot more on aquascaping and coral growth than anything. If there are tons of corals and little swimming space it makes sense you need bigger pumps to make it across the tank, right? Some tanks are aquascaped with a ton of water space even with big coral growth, and these tanks require less flow. My old 90 had around 50-60x turnover when the corals were smaller, I bumped it up around 100x turnover when the corals were in the 10"+ range and the difference was like night and day in color and polyp extension. I am a believer that flow is at least as important as light to SPS corals. If you have good flow you can slack in the lighting department.