Zoas Struggling

[NSS]

I'm having trouble figuring out why some of my Zoas are struggling. I have a mixed tank and everything else (SPS, LPS, Softies and BTAs are doing great and growing).
I have a bit of Cyano that is only giving my encrusting Monti a bit of trouble.
On the image I've labeled 8 clusters where some Zoas are doing fine and some are either dying or having problems.
(I have no noticeable pests in my tank except some small bristle worms now and then).
The red arrow is the direction where the light is coming from. I'm getting about 160PAR at the top of the Zoas and going down to 80PAR at the sand bed.
There is light flow all arround the zoas and there are no other corals around that could cause problems. Palys on the left of the image have less light and are doing good.
Here is what I've noticed:
#1 These guys seem to be stretching towards the light although they get 160PAR. The ones that get direct light are only partially open.
#2 These seem fine. No streching, no closing.
#3 These are a problem. Only partially open and the bottom ones are dying
#4 All Blue Zoas, have not grown for a year. They just barely survive.
#5 Same as #2, no problems
#6 Behavior is all over the place
#7 These are doing great
#8 same as #3 but have died. They were the furthest from the light.

Any advice?

20G Nano (12 months old)
Ai Prime 16
1x AI Nero3 Powerhead
1x Hygger Powerhead
Canister filter with media & Activated Carbon
Chaeto reactor (running 5 hours at night)
Nano Skimmer Mame
ATI Essentials+ 2 Part
Nitrate 2.0
Phos 0.02
PH 8.3
Alk 9.2
Calcium 435
Mag 1250
Sal 1.025
Temp 80F

 

[Katherine Corals]

Hi friend, I have a 115 gallon hydroponic tub that is filled with zoas and growing quit well. I use to have problems, much like yours where I had the right lighting and the right flow and they would slowly melt away, or just survive. here is how I changed that from happening. First, I got an ICP test done. I found I was low in iodine, Flouride, and a few other elements. Secondly, I increased flow a little more..
Youre welcome to check out my build thread for the parameters I run!

 

[LordofCinder]

the zoa's look like satellite dishes, it means they are begging for more light. Try increasing the PAR and see how they react.

 

[NSS]

the zoa's look like satellite dishes, it means they are begging for more light. Try increasing the PAR and see how they react.

Thanks for the advice. To me it seems that 160PAR is enough (if not too much) for Zoas. They are stretching though and that contradicts the rel high PAR value. I've read that some Zoas stretch and only partially open because of too much light. (Not sure if that is even correct). The green Hawaiian People Eaters seem perfectly fine though and don't stretch at all compared to some of the others. The orange one's at the top almost seem irritated by too much light.

 

[LordofCinder]

Sorry if I misunderstood. I thought the PAR on the sandbed is 80, and I see the zoa's on the sandbed.

 

[NSS]

Sorry if I misunderstood. I thought the PAR on the sandbed is 80, and I see the zoa's on the sandbed.

the upper most Zoas get 160PAR, the lowest I guess a bit less but still over 100PAR. The light comes in at an angle so going out and down makes a big difference in PAR

 

[LordofCinder]

what percentage is your light set at?

 

[NSS]

what percentage is your light set at?

it is set quite high so I can get between 200-300 PAR for my SPS at the top.

 

[george9]

I had my zoas in 100-150 PAR but they didn't really take off until I moved them higher into 300ish PAR and high flow. They're growing like WEEDS now. I had periodic issues with colonies closing very easily when kept lower in the tank but in higher light and higher flow they stay fully open and are very 'alert'. It also takes a lot more effort from snails or nearby fish or pods to scare them into closing so they seem 'stronger' and more confident if that makes sense.

My recommendation would be to increase the lighting on them. Zoas can take a lot more light than a lot of people think IME. Starting Red Sea AB+ dosing daily also has done wonders for growth.

My tank temp recently spiked a bit to around 82, (it usually doesn't climb above 79) and one of my colonies was clearly irritated and half closed the next day. I spot fed them 2 days in a row with aminos and benepets and they're back to being fully open, so maybe try feeding them a bit as well.

 

[Katherine Corals]

I had my zoas in 100-150 PAR but they didn't really take off until I moved them higher into 300ish PAR and high flow. They're growing like WEEDS now. I had periodic issues with colonies closing very easily when kept lower in the tank but in higher light and higher flow they stay fully open and are very 'alert'. It also takes a lot more effort from snails or nearby fish or pods to scare them into closing so they seem 'stronger' and more confident if that makes sense.

My recommendation would be to increase the lighting on them. Zoas can take a lot more light than a lot of people think IME. Starting Red Sea AB+ dosing daily also has done wonders for growth.

My tank temp recently spiked a bit to around 82, (it usually doesn't climb above 79) and one of my colonies was clearly irritated and half closed the next day. I spot fed them 2 days in a row with aminos and benepets and they're back to being fully open, so maybe try feeding them a bit as well.

This is true, I found that my zoas do much better under higher flow! I still run about 150 PAR though.

 

[george9]

This is true, I found that my zoas do much better under higher flow! I still run about 150 PAR though.

Yeah I found they like to be in enough flow to keep their little skirts wiggling but not too much where it’s ripping them apart, it also keeps detritus from building up.

When I moved mine up, I didn’t realize PAR was that high until I got a PAR meter months later. Im actually lucky I didn’t fry them with 300 PAR lol. I guess my point is they can definitely take more than 150 and might help in OP’s case given some of them look like they’re trying to reach for more.

Also taking the entire rock of zoas and giving them a brief Iodine dip may help them as well.

 

[NSS]

Thanks everyone for the suggestions so far. I will try with some more PAR first and see what happens over the next 2 weeks. Also, I might have been a bit too confident about not having pests in the tank. I just discovered a Vermetid snail between that Zoa cluster that is "reaching for light". That might be disturbing some of the Zoas, but I also don't feel like that is the reason why some of them are stretching like that.
Removing the Vermetide and raising the PAR a bit.