Can't keep SPS alive

[Jason McK]

I am wondering if anyone can help. I have attempted to keep Montipora digitata, Montipora capricornis and a Staghorn Acropora, I have yet to see any polyps from my Digitata I've had it about 4 months, with zero growth. My Capricrnis turned white and coraline algae grew over it with in two months.
I have a 75G with 2X250w 6500K MH and 2X 110 VHO actinics. My water parameters are good with zero ammonia and nitrite, nitrate is <5 and Phosphates are <.5
Ca is at 350 and Alk fluctuates from 7 to 10dKH and during the day my PH is steady at 8.3


Any thoughts would be great

Thanks
J

[Jack]

These are often difficult questions to ask because there are so many possible answers.

What have you got for circulation/water motion?

[Jason McK]

I agree, I have quizzed everyone and reread many chapters of Aquarium Corals by Eric Borneman
I have 4 PH w/ 2 returns to ensure circulation and have arranged them several time to ensure each SPS is getting good circ. I will be replacing 2 with a stream 6060 this week end.

J

[Aquattro]

You've probably mentioned this before, but what have you got for rock/sand? Nitrate should be 0 and PO4 as close to 0 as possible. Having enough rock and/or sand should eliminate nitrates all together. How old are the bulbs? Shouldn't matter, but good to know.
Digitata is known to grow like a weed, so 4 months and you should be pruning the excess.
What is the temp? And as Jack said, circulation?

[Jason McK]

I have 100bls. of LR and 3.5-5inch sugar size Aragamax. My bulbs are about 5 months old. As for the temp like most this summer has had the tank fluctuating quite a bit. from 79-83 with a few days when it reached 84.


Thanks for the very fast response guys

J

[Aquattro]

That temp is fine. Are these pieces up high in direct light? I'm also sure PO4 needs to be less that 0.02ppm (guessing) or growth is slowed/inhibited in calcifying corals. Maybe look closer at that side of things.

[Canadian Man]

how old is the tank? or how long has it been running?

I have 4 colors of digitata. the purple,yellow and green grow like crazy. The red that I have has almost shown no growth in about 10 months.

[robbyville]

One possible thought that might be a cause of slow or negligeable growth is your CA at 350. I believe that it should be in the 430-460 range.

Honestly, I am having similar troubles right now. Somehave said that Alk swings could also be a part of the problem. A possible solution of course is a Ca reactor which helps to keep the entire system in balance if you are not already using one. I am looking to get one but as always finances are the issue! In the short term, I try to keep the system stable using buffer and Ca supplements.

Good luck,

Rob

[zulu_principle]

Are you using RO/DI water ?

What else has been successful in the system ?

Fish, Inverts and corals ?

[Jason McK]

I have what I thought to be a very healthy tank.
I currently have
Corals
Plerogyra Bubble Coral (Green)
Trachyphyllia Red Brain
Caulastrea Green Candy Cane
Euphyllia Greaan frogspawn
Euphyllia Green Hammer
Dendronephthya Carnation coral
Capnella Kenya Coral
Sinularia Devils hand
Studeriotes christmas tree coral
Sacrophyton toad stool
Lobophytum Cabbage coral
assorted mushrooms
Green star poyps

Inverts
BTA
2 Maxima Clams
1 cleaner shrimp
1 peppermint shrimp
1 coral banded shrimp
various hermit crabs
Various snails
1 very elusive mantis shrimp
Fish
1 Bicoloured Blenny
3 Blue/Green Chromis
2 perc Clowns
1 Whitecheek Surgeonfish
1 lined Blenny

Wholey cow I should copy this some were I'd never really done inventory before.
That's it the whole tank