Ok here is what I can test and know about my system. The system is over 2 years old, but it used to be FOWLR but I've been running for 6 months as a BB with live rock and skimmer as the only means of filtration.
PH = 8.4
Nitrite = 0
Nitrate = 0
Ammonia = 0
CA = 440
KH = 8.1
ALK = 2.9
MG = 1500
Temp = 79
Salinity - 1.26
Over a month ago I had coraline algae growing on the back wall but its stop and green fluffy algae has taken over but now slowing dieing off itself. I don't know if this is because I stop using purple up, I stop since I read it wasn't needed as long as I'm using Kalk. I keep up with weekly or every other week water changes about 10g just to remove the detritus from the bottom. I thought my issue was phosphates when I got my Hanna Checker I was at .15 now I'm at .02 so I know thats not my issue.
Water flow - I've been moving corals and power heads also changing Votech programming for different settings just to find what these zoa/palys like.
Lighting - I would have thought (4) 54watt T5 API lights would be enough? I always wonder if my issue is not having a MH lighting.
Corals - I have xennia (waving not plusing) which has shrunk up so much its weird nt waving at this point since they are just stubs. I also have a ducan, frogspawn, brain coral, kenai, candy cane, monti, and some green star polyps which are all doing fair/ok nothing unbelievalbe just sticking around but not much if any growth from them in the last few months. I recently had a few zoa's that melted which caused me to be alarmed and I'm noticing flat worms but I don't see any on the zoa's so I'm thinking its something else. I was hoping the 6 line would eat them.
Fish- 6 line wasser, hawk fish, lawn mower blenny.
Crabs - 1 emerald crab, 5 red/blue legs
Snail - 4 astera, 6 turbos
I feed the fish/coral New Life Spectrum Marine Fish Formula fish formula pellets twice a day only 10/15 pellets the most. Also I feed cyclops and mysis shrimp frozen but dethrawed then rinsed ever once a week.
Algaes - bubble algae is starting to grown in more spots which really sucks, hair algae on a few rocks that is very strong looks like a nice place to play scoccer LOL. This is the reason I got the Lawn Mower Blenny. Also green flim algae on the bottom and on all surfaces which I scrap every 3-4 days.
Make up water is Kalk+2 mixed with RO/DI water. Evaporation is about 3/4 gallons a day.
Things I have done the last few days to try and help what ever is going on with the tank. I have stopped skimming, moved power heads, moved a few corals and added a HOB filter with standard flose/carbon pad filter just to get the film off the surface (no over flow or sump, yes this sucks.)