I breed clownfish. Last year, I bought these two 33 gallon tanks and built this custom stand. Its plumbed to a 27 gallon sump. Each tank is divided into 6 bays. Every 3 bays share an intake/return. I also run bare-bottom and clean the bottom floor every other day with a tank-vac to keep the bottom clean because I feed 3-4x a day (to promote egg laying)

Since I moved all of my clown pairs into this setup (vs the 10g individually plumbed setup I had prior), I've battled dinos/cyano and high nitrates. I don't run the lights very often because of it. I've tried to go a few days with full blackout with no luck. I don't want to even put their nems in here until I figure it out. Right now, they only have live rock and their clay pot.

I'm waiting on my bigger sump to get here (40g) and I'm definitely adding more rock when it arrives. I'm also thinking the bays may not be getting enough surface water flow so I'm having some custom 3d printed dividers made that have more hole/slots for better flow.

Do you think I would benefit from adding sand? I'm going to do a huge overhaul on the tanks. I need to drain 80% so that I can I stall the new dividers. If the consensus is to add sand, then I will pull out all of the clowns, scrub the tank down, add the new bays/sand and then refill it with fresh salt. I'm not sure if I wanted to do that, in case it would disrupt their egg laying cycles (some are laying and some are not yet).

Or do you think once I get a bigger sump and increase bio media, it would help enough? Any other ideas would be appreciated.

Also, when I got these tanks, they already had that frosted over look to parts of it. What's the best way to clean the glass?