55 gallon FOWLR flow help

[Awork78]

Hi all, new member here.

I was in the hobby around 2001-2005 with a 45 gallon tall FOWLR tank and man, have things changed.

I currently have a 55 gallon (standard rectangle) FOWLR tank with 60 lbs of sand and 80 lbs of rock. I’m about 3 months in, finished the nitrogen cycle a month ago and currently have a coral beauty, a coral Hawkfish, 2 pencils clowns, a royal gramma, and a diamond goby. I’m at around 8 blue leg hermits, a Halloween hermit, 5 cerith snails, a conch snail, and 2 emerald crabs. Ugly phase was relatively short and light, still some residual brown, but not much. Haven’t developed green algae yet, so I supplement with nori and spirulina infused frozen foods.

I have a Fluval 307 canister with no biological media, stock foam pads, added another 30 ppl foam pad set, purigen, and polyfill. Running a Fluval Reef 4.0 light, 2 heaters keeping the tank at 78 degrees F, and an IceCap K1-50 skimmer that’s on the tail end of breaking in.

I purchased 2 Hygger HG070 18 watt wave makers and currently have them at each end of the tank angled up and towards each other as this is the only way I can agitate the entire water surface. The flow is, obviously, going from the top of each end, meeting in the middle, and going down then back out to the sides and up again to the wave makers.

I’m finding I need to run them both at the lowest setting (30%) or my sand starts to dune up in spots. What could I do differently with flow in this tank with my equipment? What would be best to get most of the water to the filter inlet while still having enough surface agitation?

 

[Mr. Mojo Rising]

New sand is easily moved by the flow, it gets packed down in time. Also a tank with no coral yet has wide open flow but as corals grow they fill up space and flow needs to be adjusted, how much rock you have or don't have also impacts the flow.

My 40 breeder has 2 gyres plus the return flow plus a jebao powerhead behind the rocks.

 

[Awork78]

For surface agitation, do you need the entire surface agitated, or just some of it? I noticed I’ll get an oily stagnant patch on one end using just one wave maker as though the surface flow doesn’t quite reach the other end, but I’ll still be getting a fairly strong circular current through the tank. I like that having two agitates the entire surface, but hate the flow in the water column. I feel like particulate matter isn’t reaching the filter inlet efficiently. It’s more just circulating throughout the display across the top to the center, down to the bottom, then back out to the sides and up.

I’d like to figure out a way to achieve full surface agitation while still maintaining a nice circular flow to get everything going back to the filter inlet under the wave maker at one end. Idk, this and microbubbles from my skimmer gate valve/outlet are my two biggest issues currently.

 

[Mr. Mojo Rising]

I like good agitation all the way across, otherwise as you mention, you get muck build up in some spots. I can only say we all feel your pain, getting the flow right is one of the hardest parts of setting up the tank IMO. I'm never happy with the flow in my own tanks and always trying to improve. Good luck.

 

[Awork78]

Alright, I pulled one of the Hygger HG070 18 watt wave makers out of the tank. I put a mini wave maker on the side near the skimmer just for some more surface agitation… it barely puts out flow, just enough to ripple the surface water. The Hygger HG070 is set at 30%, lowest it’ll go, aimed angled at the surface and towards the other end of the tank.

The water a circulating well, but it seems too strong. My clowns and royal gramma are on the side of the tank under the Hygger HG070 where the water seems calmest. My new diamond goby is on the sand on that side as well with his head facing the flow. My coral beauty is swimming around everywhere, but I can tell it’s being pushed somewhat towards that end when it stops to nip at the rock. Inverts don’t seem to care, and the hawkfish just does whatever he wants all over the tank.

Would removing the impeller/fan blades from one side of the HG070 be a worthwhile “mod” to cut the flow down? Angling the ends different directions maybe? This flow issue is a headache and a half. I also think the flow at the opposite end is pulling microbubbles out of the skimmer outlet… maybe