tank not doing well; please help

rica5tully

New member
Hi, I'm new to Nano tanks and my tank just isn't doing well. Any suggestions would really be appreciated...

I recently downsized from a 72-gallon bowfront. My lighting was just powercompacts and I had low to moderate flow in tank. I had a sump and a Euroreef skimmer. For corals, I had pulsing xenia, orange monti-cap, green pocilopora-digi, candy cains, GSP, mushrooms, frogspawn, hammer coral leathers and some other misc. corals. Everything grew like crazy and was super healthy. For space/budget reasons, I had to take it down, and decided to move into a 20-gallon nano.

I bought a hydora powerhead and I'm running an Aqua-C remora skimmer as well as an AquaClear HOB filter with sponges for mechanical filtration. So there is a decent amount of flow in the tank. I have Tech T-5 lights (2x24) which is a huge increase in lighting with nice parabolic reflectors. These are my parameters:

Temp = 79-80F
PH = 7.8
Alk = 8
Calcium = 380-400
Ammonia = 0
Nitrites = 0
Nitrates = 0
SG = 1.025-1.026 (some fluctuation with water changes)
It's a 20-gallon tank and I change 2.5 gallons a week with Reef Crystals.

Fish: Six-line Wrasse, bi-color blenny, Cinnamon clown
Inverts: coral banded shrimp, hermits, snails, serpent star

Corals:
green pocilopora-digi (now faded with only one branch still barely showing polyps)
orange monti-cap (faded; one piece is dead, the other is close)
purpose mushrooms (shriveled)
GSP - looking great
Candy Cane - looking great
Hammer coral - fair; polyps look o.k. but it's not growing
I also have some VERY healthy aiptasia anenomes (wouldn't you know)

So that's my problem. I set this tank up about 4 months ago and it is just languishing. I can't think of any reason why the corals are struggling so much. I have lots of purple algae, so it doesn't seem to be a calcium problem (since the SPS are especially bad).

Does anyone have any thoughts or suggestions? It would be a big help.

Thank you,
Eric Tully
 
Whats your water source, Tap? RO/DI? Whats the TDS?

(some fluctuation with water changes)

Try and keep things as stable as possible, nanos are notoriously unstable to begin with, so do what you can to keep it from fluctuations.

Again, SPS don't like change, light/flow both should be changed slowly
 
Right, I forgot to mention that. My water source for changes is RODI water with a TDS of about 7-8.

Good point about fluctuation. It's difficult. But do you think it would be responsible for the sorry state of the corals?
 
It's probably time to change the DI filter. Your TDS should be 0.

I'd also watch the heat. Is it constant at 79-80? I've had mine creap up in temp sometimes.
 
Sounds like your bio-load is too much for that size system. 7.8 ph before the lights come on or right before they go out?
 
Chemical warfare? If the shrooms are shrivelled they could be releasing crap that is harming the SPS. Any chemical media (Carbon, Chemi-Pure, Purigen) currently being used?

Bioload seems fine (Except for the star but I am not a fan of stars in nano's).
 
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