Help my Zoa's - Browning :-(

[LetoII]

Hello all have had my tank for about a year now. It's a RSM130 34 G, with an added MP10 and a Tunze Nano 9002 skimmer. I run CPE and Purigen, also have Phospho ban. Nitrite is at 0 and Nitrate 15-20 ppm. Never read any phosphates but had macro algae growing and battled bryo.

My problem is that my zoa's went from being amazing looking to almost lifeless brown husks. I've recently upgraded the lighting from the stock 2x55x PC to 4x24w T5 Aquatic Life Fixture. I expected to see a sudden change in my zoa's but I haven't. It's been about 3 weeks now and really no change. I will be upgrading the bulbs to 2x ATI Blue Plus 1x Figi Purple 1x Aquablue Special.

I have an issue with those vermatid snail's who's silk disturbs them that I am attempting to solve. But I don't believe that is the sole issue.

Here are some photos to help diagnose. Top is what they were weeks after buying. Bottom is now.

 

[Lamball1]

Zooanthids are very sensitive to the light that they are under. Generally they like medium to stronger lighting. An intense light can dull their colours but so can too little light. Experiment a bit with some different lights and the position of the zooanthids within the tank.

 

[LetoII]

Thanks.

 

[Scopus Tang]

In addition to lighting, alkalinity swings as well as nutrient build-ups, followed by rapid water changes to bring parameters back into line will also cause many polyp to brown out. Once they've browned out, it can take several months before they regain their bright colors. Proper lighting, patience and staying on top of water quality is required to bring them back to their full color. Best of luck.