135 Gallon reef tank - crashing

[KirM]

My tank has been running for about 18 months. 137 gallon
Yellow tang, blue tang, 2 clown fish, 1 wrasse, 1 goby, 1 chromis, 1 firefish

RODI used to topup to the tank with ATO (filters were not changed and TDS was around 56 - for a few weeks until it was realized and changed a week ago. TDS is now 0 but the tank is so bad.

Temp 78.6 F
Ca 420
Mg 1390
Phos 0.2
Salinity 1.027
Alk 7.3
pH 7.8
Ammonium 0
Nitrite 0
Nitrate 6

Only the alkalinity has been a bit lower for a couple months.

I do a 40% water change monthly. Water parameters are stable at each water change.
ReeFi lights
Protein skimmer

Corals were doing well. Fish were doing well for a few months.

Then cyano bacteria started taking over the rocks and sand. The back wall of the tank has a sort of wavy thing growing on it.

Treated with the recommended Red Slime powder to kill the cyano. Lights off for 3 days. Then an 80% water change in the display tank.

Lost multiple corals after this.

A week later the cyano is back and more corals are dying. Fish and CUC appear to be fine.

I do not know why this happened. Do not know what else to do to fix this problem.

Help. Would really appreciate any and all advice.

 

[Soilworker]

Treated with the recommended Red Slime powder to kill the cyano. Lights off for 3 days. Then an 80% water change in the display tank.

This seemed like an extreme approach to me. This is a huge change in your water chemistry and lighting and likely stressed your corals.

You ran with high TDS water for 3 weeks, it will likely take at least 3 weeks to get out of your situation.

If it were me I would have gone with doing a big dose of pods and then feed phyto daily. This alone took care of my cyano problem and kept it away rather than the one-time solution that seems to come with chemical treatments.

I would also run carbon to take out whatever was causing the high TDS and then do weekly water changes of 20%. Over 3 to 4 weeks I suspect you'd see an improvement.

As for the hair algae on the back of your tank, you'll need to manually scrap and remove it and then get some larger snails to keep it under control.

Again these steps are what worked for me, your situation might be different.

 

[Soilworker]

For pods and phyto I've been using @Eldredge \ https://reefplantation.com/ and been really impressed with them.

 

[KirM]

This seemed like an extreme approach to me. This is a huge change in your water chemistry and lighting and likely stressed your corals.

You ran with high TDS water for 3 weeks, it will likely take at least 3 weeks to get out of your situation.

If it were me I would have gone with doing a big dose of pods and then feed phyto daily. This alone took care of my cyano problem and kept it away rather than the one-time solution that seems to come with chemical treatments.

I would also run carbon to take out whatever was causing the high TDS and then do weekly water changes of 20%. Over 3 to 4 weeks I suspect you'd see an improvement.

As for the hair algae on the back of your tank, you'll need to manually scrap and remove it and then get some larger snails to keep it under control.

Again these steps are what worked for me, your situation might be different.

Thank you! I appreciate the advice. The problem is so bad. I will take your advice.

 

[ShaunMc]

Feels like a couple hours and a good portion of this could be manually removed. Cleaning the walls should be simple. Some of the rocks look like they can be easy to pull out. When you do a water change. Put those rocks into the water you took out and clean with a tooth brush. Place back.

What is your CUC? What is your lighting config and schedule? What/how often are you feeding?

Some of those likely contribute, but if this was mine. I’d spend a couple hours of the next few days and just clean it. I’d turn down some whites on my lights or review my schedule. I’d look at my filtration design and I’d review my feeding.

 

[KirM]

Feels like a couple hours and a good portion of this could be manually removed. Cleaning the walls should be simple. Some of the rocks look like they can be easy to pull out. When you do a water change. Put those rocks into the water you took out and clean with a tooth brush. Place back.

What is your CUC? What is your lighting config and schedule? What/how often are you feeding?

Some of those likely contribute, but if this was mine. I’d spend a couple hours of the next few days and just clean it. I’d turn down some whites on my lights or review my schedule. I’d look at my filtration design and I’d review my feeding.

Sounds good. I will get into that! Thank you