Help with chronic decline


New member
Tank inhabitants having severe issues. I'm much more familiar with freshwater and appear to be in over my head. Any and all ideas please welcome.
The tank: 100 gallon with 30 gallon sump. Thriving for last 8 years. Inhabitants: 2 clowns, kole tang, yellow tang, 2 green chromis, 2 yellow belly damsel, fire shrimp, coral shrimp, many brittle stars, collector urchin. Corals all happy : 18" wide toadstool leather, hammer, torch, various leathers, several chalices, button polyp, zoanthid polyp, green tree coral, trumpet and many many many red and blue mushrooms
Water changed extremely consistently once per week 10-15 gallons. Water from RO made using Ontario municipal water source and premixed in large covered plastic garbage can with circ pump until next water change. Salinity in tank and reservoir always 1.020-1.025 measured with a refractometer.
Nitrates and phosphates checked every few months. Both negligible (no colour change) every time. Using up to date API liquid test kits. Calcium checked periodically and usually around 400ppm mark. Alk consistent around 7-9 dKH.
Refugium full of caulpera and still growing at usual rate. Protein skimmer still working well with no change in output. LED lights new Nov 2018 and wiped periodically to keep clear.
Tank moved houses March 2020 within same city. All went well. Some corals did better post move as they ended up in better places in tank. Only change to equipment was 2 less circ pumps as they didn't work after move. No change to schedule. No direct sunlight on tank. No cleaning chemicals used in tank room. Tank in dining room with open kitchen and living room.
Tried to piece together a timeline:
24 July "“ fire shrimp died. No other fish or corals cause for concern
26 Aug "“ hammers starting to stay closed, not looking great. Mushrooms thriving and taking over some polyps and leathers so attacked with Aiptasia-x, a few at a time to see if it worked.
28 Aug "“ new fish "“ banana wrasse, spotted goby, Xenia coral added after 4+ week quarantine
5 sept "“ red chalice bleaching, another dose of attacking mushrooms with Aiptasia-x
11 sept "“ torch dying. Increased water changes to twice week. Changed phos beads in sump and added carbon
18 sept "“ calcium 280ppm "“ started dosing 2-3 times per week recommended daily dose
24 sept "“ torch gone, leathers affected (not mushroom), calcium 340ppm
1 oct "“ calcium 360 ppm, KH9, many polyps gone
2 oct "“ damsel died, snail died (both 5+ years old)
3 oct "“ calcium 380ppm, Xenia still happy
6 oct "“ New RO unit and new filters
10 oct "“ calcium 400, KH 9
8 nov "“ Zoanthids still ok, xenia showing signs of not happy, chalices gone, small leathers gone, green tree weaking but still in it, large mushroom leather weakening, red and blue mushrooms not opening fully at full light like usual, calcium 400, KH 9. Wrasse hasn't been seen in a week but no body found.

Chem seems to be stable and within ranges. If contaminant coming in via water source with older RO, that was replaced a month ago and should have started correcting. If Aiptasia-x meds causing harm, there was no immediate difference following using it and the decline has been steady since before its use.
What am I missing? What else can I change or do or look at? I'm sorry for the long post, but I'm at my wits end. Thank you


Staff member
RC Mod
a 30% water change, then 20%, and another 20%, on successive days may help. Maybe do it again in a week. It's kind of a reset for an older tank. I recommend the parameters in my sig line also for softie tanks. Stop meds until after---and with luck it will make your tank less friendly to pest species.

All that done, try to sub water change routine for corrective remedies like phosp. and aiptasia. If your water's right, with a good salt brand, it should help the critters.


New member
Can't edit my original post so I'll post here. Water changes were upped in September to 2-3 times per week. Can't do more than 15 gallons at once as that is the max of the reservoir and want to fully dissolve in salt before using.
There were only 2-3 aiptasia in tank originally and was never a problem. The meds for it were used as an anti-mushroom idea and was only used twice. Haven't now used in months.
Salt is Seachem and always has been same brand. The water does, as far as I can tell, appear to be alright. So why are the corals still dying?


New member
Maybe a case of all prams up and down regularly, not stable all the time? Stability is more important then spot on in the long run. Even temps up & down take a toll if rapid & extreme, same for salinity on some creatures. Water keeping can be a chore if it gets forgotten too long then immediatly brought back too fast to correct its params.