Nitrates low, soft corals look bad, green on sand

[hawk82]

Ive been having some issues the past 2 weeks with my soft corals. Zoas, GSP, and Xenia are not doing well. Xenia is closed up, zoas are not open all the way, gsp has gone from big and fluffy to nothing but its mat. I have two finger leathers they are still doing ok, but not growing any. I also have some green on my sand, looks like green cyano. Its hard to tell, but its only on the sand, and it seems to go away at night when the lights are off. The rocks look fine, and fish are doing great. I tested my Nitrate tonight and it was only around 2. Last time I checked this it was around 15-20 and the corals were doing really good then, growing alot. What can I do? Whats the best plan of action here. My tank is a 40 breeder with a hang on reef octopus bh100 skimmer, but Ive not been running the skimmer, should I turn it on, or just leave it off? I have a canister filter I use for a place to hold carbon, gfo, and stuff, but its also empty. So Im not using any kind of chemical or skimmer filtration. I had turned both of these off in the beginning because I had a dino outbreak back in april after first starting the tank. The dinos are gone now, but I never turned the skimmer back on, or added any kind of media. Tank is 40 breeder, about 35 pounds of gulf live rock, and 40 pounds caribsea sand. It has 4 fish, clownfish, royal gramma, banggai cardinalfish, melanurus wrasse. Also about a dozen snails and hermits. I have some caulerpa prolifera growing in the tank as it came in with the live rocks, but the grow rate of it has slowed down alot also, I was pulling hand fulls out every week, not it seems to be at a stand still. Ph is 8.1, salinity 1.025, nitrate 2ish almost 0. These are the only tests I have. I use ro/di water and tds is 0. Been doing 3 gallon water changes on every week with regular instant ocean. Id like for my soft corals to thrive again, and for the green on my sand to go away. Any help would be greatly appreciated. Tank has been running since January of this year.

 

[Uncle99]

Pull the macro algae.
I don’t see the phosphate number and that would be important.
Nutrients, N and P must be trace and in balance with each other or you risk the bad algae’s, and slow growth.
As an example my N is 5ppm and Phosphate is .05.
When my N was 25ppm and P was 0.01, the cyano came, corals looked drab.
Reduced N and increased P as in the example above, Cyano gone in one week, corals inflated again

 

[hawk82]

Pull the macro algae,

All of it? I like the way it looks. The fish seem to enjoy it also.

 

[Uncle99]

All of it? I like the way it looks. The fish seem to enjoy it also.

Then keep it, but it maybe stripping the water of nutrients

 

[jt8791]

This has me curious about stocking on my next build. I’m planning on gsp and Xenia in the 30dt and chaeto and graciliara in the 20h fuge.

When I did my first tank my usual go to at the local petco and most others agreed to some extent that you have to slightly overstock for macro tanks.

Does this apply with soft corals as well?

If so I may have to put something in the fuge for the bioload. Hard to say if a 30 stocked reasonably would provide enough nutrients for all that.

Was thinking of trying to breed copepods, brine shrimp and maybe mysis shrimp in the fuge if possible so not sure a fish in there would work.

Almost wonder if you need to do less water changes or possibly less often but not sure how that will work with certain nutrients that get used up. Maybe try skipping a week and monitor your levels. That sounds like the simplest option, maybe add another fish to increase the bioload. Other than the wrasse the bottom of your tank does sound a bit empty but I’ve yet to have cardinals or a royal gramma.

 

[jt8791]

Although noting what uncle99 said, Probably should test phosphates first thing, I’ve always had a habit of doing a water change instead of testing, it takes less time but seeing the issues you are having I better order a good test kit while my 30 is cycling

 

[hawk82]

Hi, since this post Ive turned off my skimmer. That seems to have helped alot. I dont think my tank is stocked enough for a skimmer, since I have the macro growing. GSP has made a rebound and is bigger then ever.