Reef nutrition

Musing on coral coloration

I upgraded my tank about 2.5 months ago to a Nuvo 20g. The live rock is from my old tank which ran for more than an year.

Some corals have displayed good growth and some have shown no growth at all. But for most part, I am seeing a fading in the coloration for most corals. Most notable color fading is with bali green slimer. My nitrates have always been low.

Sleuthing info:
Tank: Nuvo 20g
Light: Single Kessil A160 runs at a peak intensity of 75% at a height of about 8 inches above water.
Chemistry:
Fairly constant Alk: 8-8.5 dKH, Ca: 380-400, Mg: 1300-1350 (Tested with Salifert kits), Nitrates: Undetetable with API kit (unreliable, I know, but the color is as yellow as it can be).

Water changes: Every 10 days about 2-3 gallons.
Flow: Jebao wp10 at 75% power and a small powerhead. Flow looks good and corals open up well.


Corals that displayed good growth: Pink and green birdsnest, peach digitata, orange digitata, jack o lantern, montipora setosa, Zoas: pink zippers, utter chaos, bambams and some others

Corals that haven't grown: Bali green slimer, unknown acro (brown when I got it, still brown), rainbow monti

Misc/Equipment:
Ghost skimmer that pulls out a decent amount of organics every week. Chaeto chamber at back with shows decent growth.
I have carbon, purigen and phosgard in one of the media basket. Other media basket is basic mechanical sponge, carbon and phosphate reducing sponge.

I do see little strands of algae here and there, but my emerald crab and snails keep the rock-work fairly clean.


Questions/Line of thinking:
1. Nitrates could be too low? Would dosing Acropower be a good idea? Don't want to cause a algae outbreak.
2. Considering shutting down the skimmer for a few weeks to increase nutrients (but those tiny strands of algae make me think there is a trace of nutrients in there)
3. Or maybe removing the Chaeto from my tank altogether.
4. Stronger light? My birdsnest did more than good with this same light over an year in my old tank. Relative distance and intensity from the light is about the same.


Would love to hear suggestions or thoughts. What strategies do you use for getting best coloration?
 
Sounds kind of normal to me :) You just moved a bunch of SPS into a new environment. It can take SPS 3-6 months to acclimate and color up normally especially in a newish tank.
 
It might be trace element depletion, if you have a good salt mix and can match the alk of the new water to your old water to prevent shock, do a 50% change every 2 weeks. Since your nitrate/phosphate is already zero you have nothing to lose and everything to gain. If you want to test, I would probably test iron, potassium, iodine. You are probably stripping trace elements with your chemical media and your water change amount seems really low for such a small tank. But keep feeding your fish to keep the nitrate and phosphate import going...
 
It might be trace element depletion, if you have a good salt mix and can match the alk of the new water to your old water to prevent shock, do a 50% change every 2 weeks. Since your nitrate/phosphate is already zero you have nothing to lose and everything to gain. If you want to test, I would probably test iron, potassium, iodine. You are probably stripping trace elements with your chemical media and your water change amount seems really low for such a small tank. But keep feeding your fish to keep the nitrate and phosphate import going...
Thanks @Chromis. I can try increasing my water change volume and maybe going light with the filter media. One thing I generally ignore is checking the Alk of the freshly prepared saltwater. I'll start doing it more and observe if that makes any difference.
 
I think Liz @Chromis is spot on with the trace elements. Problems with green corals is a lot of times tied to iron. I also think it would be good if you had a real number for your phosphates. Perhaps your local fish store offers water testing.
Cheers! Mark
 
She's not saying the alk will make a difference in color. She's saying the trace mineral will. You don't want to do a big water change or two like she suggested to increase the trace minerals unless the alk of the new water is pretty close to what you keep the tank at.
 
She's not saying the alk will make a difference in color. She's saying the trace mineral will. You don't want to do a big water change or two like she suggested to increase the trace minerals unless the alk of the new water is pretty close to what you keep the tank at.
Yup, understood. Just a mental note to myself to be careful with Alk when changing water. Might be one of the factors that might cause corals to stress out in a timely manner (each WC) and thus prevent optimal coloration.
 
Yup, understood. Just a mental note to myself to be careful with Alk when changing water. Might be one of the factors that might cause corals to stress out in a timely manner (each WC) and thus prevent optimal coloration.

If your tank is 8.8, and your new water is say 10, and you do a 20% water change, that only raises Alk to 9.
So I would not worry. Really only a problem if you do huge water changes and Alk is way off.
 
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