Green Digitata Help

[Justin Thain]

I'm curious if someone out there knows what my issue might be. I have had 2 green Digitata's in my tank for about 5 months now. It looks like I'm struggling with them at the moment. Although to be honest I dealt with the same issue about 2 months ago, but it didn't last this long, and they bounced back fairly quickly. My issue is that the coral will be growing beautifully with the tips being white, and then over the course of several days, I start to see the white tip fade, and then I see very small specs of algae growing on the tips (see pictures)
Here is when it looks awesome

Here is when there is algae growing on the tips.

My tank parameters are the following
Salinity - 35ppm
Alkalinity - 8.5dkh
Calcium - 425
Phosphate - 0
Nitrate - 0

Lights are three xr15 pro (gen 4)
with four T-5 as supplemental
Par level is only about 225 - 275 (max) at there current level.

Tank is 210 gallons with a 40 gallon sump

I run an algae scrubber as nutrient control

I know I have some nutrients in the tank since I have GHA growing in placing, but trying to control with CUC

Tank is 6-7 months old.

I do have 2 acros in the tank doing just fine.

Any thoughts ?

 

[LetItReef]

Flow?

 

[Justin Thain]

Flow?

Oops forgot to mention that I have 2 gyre “150” in my tank. I have plenty of flow.

 

[Dennis Cartier]

I would guess too low of nutrients with too high of Alk (for those nutrient levels). Slowly drop your Alk to 7.0 - 7.5 and the issue will probably resolve. Search for "tip burn" or "burnt tips" on here. Essentially the corals with the issue are out growing the ability for them to grow new tissue fast enough to keep pace with the speed new calcium carbonate is being deposited at the tips. Another options is to get more nutrients in the tank to keep the nutrients a little bit higher to give your corals the resources to deposit tissue fast enough to keep up with the growth rate at 8.5 Alk.

Dennis

 

[tdileo]

I would guess too low of nutrients with too high of Alk (for those nutrient levels). Slowly drop your Alk to 7.0 - 7.5 and the issue will probably resolve. Search for "tip burn" or "burnt tips" on here. Essentially the corals with the issue are out growing the ability for them to grow new tissue fast enough to keep pace with the speed new calcium carbonate is being deposited at the tips. Another options is to get more nutrients in the tank to keep the nutrients a little bit higher to give your corals the resources to deposit tissue fast enough to keep up with the growth rate at 8.5 Alk.

Dennis

Great advice and explanation. +1 to what was said here!