Hmm... Need a little help. Green Stars / Yellow polyps

[cdemeritt]

Hello all,
It has been a bit since I was last here. Life has kept me very busy.
Now I'm back with a question, that I hope maybe one of the brains of the group might be able to help with. My Green Star Polyps are doing great, ( third attempt, first two ended badly), and are spreading onto other rocks, but my Zoas and Yellow Polyps have been fading, and I don't know why.
My overall tank volume is about 55 gallons (35 display, 15 sump, 10 'fuge). lighting is 80w of marine-glow and aqua-glow florecents for 8 hrs a day, with a 6500k 175w MH bulb for 4 hrs. Flow though the system is 500gph with two 150 gph internal powerheads. I don't do many tests, as after weekly testing for 2 months had no changes. SG 1.024. weekly 10% waterchanges with DI water. average tank temp 78'f. calcium levels seem good, as coralline growth has been stable, and I need to scrape the worms off the front of the glass almost weekly. hair algae is preasant but very minor. Caulerpa Taxifola in the display is very slow growing. some Halimeda is also growing in the tank, but very slowly. Other tank inhabitants include 1 spotted molly, 3 (e-gads! not just 1 but 3) yellow tailed damsels, 1 queen conch ( fighting conch? ), 2 emeraled crabs, 1 true pepermint shrimp ( L.wurdermanni), 2 types of Mushrooms (large colonies), 1 arrow crab, and about 1 dozen blue legged hermit crabs. all have been very healthy. the last lost was my featherduster worm, almost 4 months ago. last addition was almost 7 months ago, and that was the yellow polyp rock. Feeding: about once a week about 5cc DT's live phytoplankton, 1/2 cc decapsulated brine shrimp, 1 pinch flake food, and 1 pinch spraydried phytoplankton, all mixed into a single tube and poured into different spots within the tank, to directly pass over the corals before being diluted too much.
I haven't seen anything bugging the Zoas, but they have slowly been dissappearing. the pattern of loss has been that the ones on the edge close sooner than the inner ones, then after a couple days the they don't open at all, then they seem to just dissappear. The inter ones open large and seem in purfect health. the interesting thing is that of the zoas, I got three frags on the same day, one brown (4 polyps), one cream (4 polyps), and one green (2 polyps). the brown and cream ones both dissapeard, but the green ones are now 5 polyps. all of the polyps are at about the same hight in the tank, midway, nad get about the same waterflow, just enough to keep the tenticals moving, but not so much as to move the stalks. each rock is spaced enough to keep them from touching anything else.
Anything jump out at you as why some are doing great and some are not? anything I mentioned that could be nibbling on them?

Thanks,
Chris

P.S. Never had a cyno-bloom. never had ich or other parasites. I have good pod population.

[yardboy]

Let me first say that all my experiences are anecdotal so understand that I'm no expert. I've been keeping salt tanks for just under two years now, been very rabid about it, sold many frags, had as many as 6 tanks, but only two now, well three if you count my refugium/nano reef tank.

There are many bandwagons you can jump on in this hobby, many people who look at systems with a narrow focus (the bare-bottoms, the deep sand beds, the phosphate freaks, the bacteria boys, etc.) I've decided to also form a club that attributes most of the woes of reefers to a single source - ORGANICS!)
over import and under-export of nutrients, degrading and forming high dissolved organic concentrations. (My acronym of the day - DOM-dissolved organic material!)
From your descriptions that could be your problem. I'm not saying it absolutely is, but it is a possibility. You don't mention skimming, seems that you might be somewhat overfeeding, unless I read your message wrong, and maybe waterchanges are not adequate.
Zoanthids and yellow polyps are very tough critters. I have a colony of yellows I put in my refugium and they are about to take over the rock they were set on. On the other hand, the 70 gallon system I have set up in the garage and which I don't mantain like I should (don't clean the skimmer regularly, few water changes, heavy fish load) has the parent colony and it is/was declining. That is until I removed the two year old sand bed, changed half the water, and throughly cleaned the skimmer, and wet/dry. A few days later they started looking much better. Same with the colonies of zoanthids. I felt quite bad to have distressed the tank so much with its miscare. I promise to take better care of it!
Again, I only think it is a potential problem with your tank because it was a problem with mine. At first, I thought it was heat (something else you might look into) but the improvement was so dramatic that I felt it had to be related to the nasty water in the tank.

[ObsessiveProgression]

If your water chemistry is ok, then look at the lighting.... do you have enough lighting on the edges of the tank? Perhaps the colonies in the center are establishing their territory there, and so the other ones move to the edge where they die off because of inadequate lighting.

Also, how old is this tank? have you added any new live rock? Perhaps you got one or more unwanted hitchhikers with some new live rock. I have no idea what kind of hitchhiker could do what your experiencing, but I heard of a guy who got a baby moray eel with a shipment of live rock..... the moray only came out at night, and would eat his fish. He had no idea where they were going until he saw it by chance one day.

Im not saying either of these is your issue. Just something to consider.