I've put off posting anything like this for a long time thinking I could tweak something myself and all my zoas would come back and all look healthy. However, I've now lost countless colonies over the past 4 or 5 months. Huge colonies (25+) of Clementines, blue hornets, Rastas, CARS, and the list goes on and on. You can imagine the cost. I have other colonies that seem to be fine so far. I have blondies, fruitloops, frostbites, bam bams and much more that are still doing OK but I just can't seem to figure out what is melting them. I've never thought zoas could be the most delicate corals in my tank because I don't have a problem with anything else. I'm basically going to ramble on with everything I can think of that is going on in my tank and I'd appreciate any experienced insights. First off, my parameters:
Nitrate: just checked and it's been consistently between 5 and 10ppm for as long as I can remember. I can't seem to get them any lower than 5 regardless of how many water changes.
Phosphates: I just bought a Hanna checker and it read as 0 twice.
Salinity: 1.023-1.025 pretty consistently.
Temp: 78
Alk: 8.4-9
Calcium: 420-450
pH: abt 8.1
I have read that blue hippos can eat zoas and I have one but I've never seen it nipping at any corals. Ever. Is it possible? I guess but it seems odd that the entire colony one at a time would suddenly close and then over time melt when zoas around them seem to be fine.
I have flatworms but I don't think they are harmful to zoas. I've never seen any other pest. No astrea, no snails that I've ever noticed. I've looked closely with the naked eye and have never discovered any pest. Could there still be something I'm not noticing with my naked eye? Possibly.
I've checked my colonies to notice what might look like Fungus or pox and although it seems like there's an algae slime covering them sometimes when they're closed, I've never noticed what looks like the pox compared to the photos I've seen. I've also tried coral dips of Furan 2, hydrogen peroxide, Coral RX and nothing seems to make a difference and the colonies just eventually melt anyway.
I have a 50g Cadlights II and I've automated everything. I have the BRS dosing pumps dosing Alk and Calcium throughout the day so there should be pretty consistent levels. I have an ATO. I run GFO and activated carbon in a BRS reactor. I even removed it about a week ago to see if that made any difference. Doesn't seem to yet. I run my protein skimmer 24/7.
I have been adjusting my lighting to try to see if the zoas look better or worse. Some of the SPS corals as they've grown or as I've added have started to block some of the lighting. Is that the cause? Could be. Kind of doubt it though because I've lost zoas from all over the tank. I have a Maxspect razor 16k 160w. Right now my lights are scheduled to start from 1% blue at 9:30 am to 80% whites and 80% blue by noon. They stay that way until 4pm where they go to 60% blues only by 10pm. Then down to 1% blue by 11pm.
As far as flow, i upgraded to two MP10s. I had them on the back of the tank near the top pointing towards the front for several weeks, maybe a month. I then experimented with putting one on the side in the middle and after about a month things looked worse so I just moved it back to the back of the tank. I've tried different flow methods. The flow could be the problem but even after several days or weeks, I don't see the zoas really improving. I would think that SPSs would be much more finicky to light and flow and so far, they seems to be doing well. I still have good polyp extension and color, at least as far as I can tell. They don't look as great as what I've seen in others' tanks but I attribute that to my lighting and simply because they haven't been in the tank as long and adjusted.
I used to do about 5g water change a week using Instant Ocean and I've since been doing about 10g a week to see if that would make a difference.
As far as food and dosing goes, I dose about 3 times a week Oyster Feast and I also feed things like Golden Pearls, dry copepods. I also dose Korallen-Zucht Amino Acid Concentrate about 4 times a week (when I remember) but I haven't noticed any drastic difference.
Here are some pics. Unfortunately, I can't get any decent pics close up. I really need a good macro lens.
This bam bam colony is still relatively good but it does seem like it's thinned out and several polyps stay small or closed now.
You can't really see well but the top rock has a ton of closed up Palys of what used to be very large pink palys. This is the latest huge colony that seems to have closed up.