Black on top of rock

[leighproct]

I am having difficulty with my 120g saltwater aquarium. I can not keep any corals whatsoever. They die within 24 hrs of introducing them into the tank. I have several fish that have had for over 8 months now and doing well but can’t seem to get corals to go. All my parameters are good. 0 TDS RO water. Water changes regularly. One thing I have noticed is the dry rock that I have in the tank has black all over the top of the rocks. I can brush it off with a toothbrush and have no idea if this is an underlying problem?
1.025 salinity
0 Nitrate
0 Nitrite
Ammonia 0ppm
11 KH Alkalinity
8.2 PH
Water temp 75

 

[Reefkeepers Archive]

Could be some sort of algae, if all you're corals die that quickly, or if all your corals die than I'd definitely get an ICP test done. What kind of corals do you add?

 

[leighproct]

Pulsing xenia
Zoas
Kenya tree

 

[Reefkeepers Archive]

Pulsing xenia
Zoas
Kenya tree

Definitely get an ICP test, those corals should not be dying

 

[jda]

If it is soft, it is likely cyano or some other soft of matting bacteria. However, hard to tell from the photos.

 

[jda]

IMO, ICP is not going to tell you anything. Any compound that can kill a coral in a day won't show up in an ICP test - they don't test for compounds anyway.

Are you sure that the temp, salinity and other basics are accurate? Have you double and triple checked your instruments?

 

[leighproct]

I have spent a small fortune on test kits because this is maddening. Salinity and temp triple checked.
New kit today.
Nitrate 0
Nitrite 0
Ammonia 0.25ppm
PH 8.4
Water temp 75

 

[leighproct]

Could the rocks be decomposing or something causing the ammonia to rise? Would this kill off the Corals.

 

[waqas_01]

What kind of test kits are you using to test these values?

If the values are actually correct, stop doing water changes for a bit and let your nitrates get up to 5-10ppm. I would trust salifert nitrate test kits or a hanna high range nitrate checker.

You also want a hanna low range phosphate or phosphorus checker. Ensure you're not 0 for phosphorus/phosphate. You want to be in the 0.03-0.1 ppm phosphate range.

Running zeroes for either or both of these will starve your corals. I was getting polyp bailout within a week at the beginning when my nitrates were reading zero.

Lastly, let your temperature slowly get up to 77-78F. Most LFS tanks are running at the 77-78F mark, so you might just be shocking them putting them in colder water.

 

[Mr. Mojo Rising]

can you post a tank pic?

Do you have any flow in the tank?

 

[leighproct]

I have flow yes.

 

[tnw50cal]

You need a way better light if you want to keep corals.

 

[leighproct]

What kind of test kits are you using to test these values?

If the values are actually correct, stop doing water changes for a bit and let your nitrates get up to 5-10ppm. I would trust salifert nitrate test kits or a hanna high range nitrate checker.

You also want a hanna low range phosphate or phosphorus checker. Ensure you're not 0 for phosphorus/phosphate. You want to be in the 0.03-0.1 ppm phosphate range.

Running zeroes for either or both of these will starve your corals. I was getting polyp bailout within a week at the beginning when my nitrates were reading zero.

Lastly, let your temperature slowly get up to 77-78F. Most LFS tanks are running at the 77-78F mark, so you might just be shocking them putting them in colder water.

You need a way better light if you want to keep corals.

Ok but would that kill the corals in 24hr?

 

[leighproct]

Ok but would that kill the corals in 24hr?

What would you recommend for 120 gallon tank?

 

[Mr. Mojo Rising]

Personally I would say you need better flow, those little amazon powerheads are not very good and won't cut it for a large tank like that..

The water surface also looks very flat, you should point one of those powerheads at the water surface to agitate the surface, and help put more oxygen into the water. Better flow will help your tank overall.

Also need more rock, should be close to a pound per gallon, more rock provides more space for healthy bacteria to grow.

 

[leighproct]

Personally I would say you need better flow, those little amazon powerheads are not very good and won't cut it for a large tank like that..

The water surface also looks very flat, you should point one of those powerheads at the water surface to agitate the surface, and help put more oxygen into the water. Better flow will help your tank overall.

Also need more rock, should be close to a pound per gallon, more rock provides more space for healthy bacteria to grow.

Do you think the black in the rock is a problem though? I have had the power head more at the top but have been playing around with water flow. I will point them more to the surface. As for the two on the bottom right are you saying I need more powerful ones down there?

 

[leighproct]

Do you think the black in the rock is a problem though? I have had the power head more at the top but have been playing around with water flow. I will point them more to the surface. As for the two on the bottom right are you saying I need more powerful ones down there?

 

[vetteguy53081]

Bacterial matting often from a substance known as mulm which establishes itself. You can remove rock to a container of tank water and scrub with a firm brush and some 3% Peroxide and return to tank
Pitho crabs, pencil urchins and ninja star snails will often help keep control Once the scrubbing has been done

 

[leighproct]

Bacterial matting often from a substance known as mulm which establishes itself. You can remove rock to a container of tank water and scrub with a firm brush and some 3% Peroxide and return to tank
Pitho crabs, pencil urchins and ninja star snails will often help keep control Once the scrubbing has been done

How much peroxide? Won’t that hurt the fish?

 

[Mr. Mojo Rising]

Do you think the black in the rock is a problem though? I have had the power head more at the top but have been playing around with water flow. I will point them more to the surface. As for the two on the bottom right are you saying I need more powerful ones down there?

yup, need stronger/better flow in your tank, those are just tiny little nano pwerheads. Stuff coming to rest on the rocks and growing into a mat is a sign of not enough flow IMO