Setting up flow in my soft coral dominated tank

[LeRenard]

Hi soft coral forum!

I'm still a newb going through the typical ups and downs starting up my 36 gallon reef tank. As I've learned more about the hobby and the things I like to keep in my tank, I've realized I like soft corals quite a bit for their movement. I had a minor unexplained disaster in my tank recently that caused the loss of my small Kenya Tree and Xenia frags (I don't know why only those two- everything else survived unscathed including all my inverts and my zoas. I think some chlorine in my tap water made it through my RO/DI and into the ATO water I've added additional DI resin and test the water first now) but I've got things back on track and stable and I'm looking at making my tank a better home for soft corals going forward because I like them.

One thing I'm trying to figure out is how most people handle flow in their soft coral dominated reef tanks. I've got a 36 gallon bow front with two Jebao RW-4s. My sump return is maybe 400gph spread along the back wall of my tank behind the rocks, and the two RW-4s are on each side of the tank facing the bowfront glass. When my Kenya Trees and Xenia were healthy, turning both on their lowest setting was enough to lay the Kenya tree over flat and for the xenia not to pulse, so typically I would have one running on it's lowest setting and the other off or in a low "pulse" setting.

What puzzles me is that I'll look on youtube at some of the gorgeous softie tanks out there and they'll be running some huge koralia and usually only one, and their xenia is still pulsing and things are just slightly swaying in the current.

Since I'm reconfiguring things a bit, how do people get that beautiful gentle motion I see in their tanks while running these huge koralias? And how do these lower flow tanks keep the bottom so clean? Just as a note, I'm not blasting anything directly. I usually bounce them off the glass or rocks or up to the surface, but it usually sets up circulation in the tank enough to flatten everything out like it's being blown around by jet exhaust. I'm also running them on setting 1 which is supposedly about 150-200gph.

Should I take one out? Should I bother with having one doing a "pulse" so it's not all laminar flow?

 

[Mock]

I will toss in my 2 cents.

130-1000 GPH is what a RW-4 is rated. @ 15 times your turn over that would be only 540. 15x is enough for stonies and to blast sand everywhere no matter what. Bare bottom tanks run in this zone or higher.

With that said, at the lowest setting you are still at 5x your total turn over not to mention your return pump, I have no idea what it is producing but 400gph, head loss calculator will show about what you are getting. Its still all a little extreme for a 36.

Usually a good rule of thumb is 10x per hour the turn over inside the tank and 3 to 5 times an hour from sump to tank.... You are probably okay on the sump to tank turn over but with two RW-4s you should be, as you are, laying over your corals.

My suggestion, take one out. Run the other on the lowest setting until you find out either if you like pulsing wave motion or just a random or what. Once you find this out, start increasing the power on your pump to a point where you are getting good flow, but not laying things over and let it run for a couple days. Your corals will adjust, clamp down a little harder, bases with stiffen, things will acclimate and then, if you find you are having dead spots, increase a little more each couple days until you are getting the flow you want.

Dont try to do it all in a day because corals will get used to their surroundings, you may not see it in the videos and the photos you are looking at but those like me that are running big pumps in our tanks and our corals are taking it, its because we acclimate them to take it.

Mine were at one time about to fall over too but now I run two Jeabo WP-40s and two MP-40s along with a 70x blueline as my return in a 250 gallon tank. Yes I have a sand free spot in the middle but all my coral have learned to take it and stand up tall with short stocky bases.

I personally use my MP-40s on Reef Crest which is a random flow and the two WP-40s on Pulse for a side to side motion.

 

[LeRenard]

My return pump is ridiculously larger than it needs to be (a Jebao DC-9000) because I was shipped the wrong pump and they ended up just letting me keep it. Being a DC pump I just dial it in for about 400gph which I estimate because my overflow is rated for about 500, so I turned it up as high as it would go until my overflow couldn't keep up then backed it down a notch. If I cranked it up I could easily overflow the tank and empty my sump. At one point I considered putting a SCWD on it and just getting rid of the powerheads in the tank completely but I was advised against that.

I think I've just been misinterpreting people's flow recommendations by 1) seeing numbers for SPS 2) Seeing numbers for acclimated corals and 3) misunderstanding that the numbers were a total, not a per device guideline

I think I'm going to take your advice and back down to one for a bit and ramp them up slowly over time if I need to, thanks for those guidelines, they seem way more realistic than what I was going by before. I was getting confused because I'd see a larger figure, decide that it looked like too much in my tank, then look at a nice softy tank with a huge powerhead where things weren't being blown apart and not understanding why my tank was different.

 

[Tzwizzle]

IMO the important thing is intermittent flow rather then total gallons of movement. If you've got a large return I would point one or 2 power heads that can do intermittent to intersect and create some random flow patterns.

Softies seems to handle the occasional strong bursts better then LPS. Also the random strong burst of flow may help leathers remove their slime coat. If they are pinned down in one position without changing directions then you may want to adjust your flow.

I think you'd be happier downsizing your return pump. You can always run a T with a ball valve back into the sumps but depending on how much you tune down the flow you could jeopardize your pump in the long term. I made the mistake of buying too big of a return (twice actually). Worth the cost to down size and I have a spare in case of emergency.