Are these Diatoms?

[Darbna]

So I have had the red sand for about 2-3 weeks now. Done 2 huge water changes over the last 2 weeks. 40 Gallons each time. All corals seem happy accept the Wilsoni on the bottom, which has some tissue Rescission. It started prior to anything with the sand. I have been running the Alk a little higher to see if it would help. Its not. No algae or red on rocks. Any Suggestions is appreciated. I am at the point of frustration.

Parameters

Ammonia- 0
Nitrates-0
Phospate- 0
Calcium- 440
Alk- 10.4
PH- 8.1
Mag- 1380

 

[cromag27]

Looks like diatoms. what is your water source when you do water changes? diatoms are generally caused by excess silicates which can come from rodi water than is not at/around 0 tds, or from newly introduced plastics to your system. have you added any new equipment lately? they are more prevalent in newer setups but they can come and go in established tanks as well.

 

[Darbna]

Looks like diatoms. what is your water source when you do water changes? diatoms are generally caused by excess silicates which can come from rodi water than is not at/around 0 tds, or from newly introduced plastics to your system. have you added any new equipment lately? they are more prevalent in newer setups but they can come and go in established tanks as well.

I am relativly new, only about 6-7 months in. I just added a phosphate and carbon reactor and one additional powerhead. Went through some Dino's 3 months in and killed them with H2O2 and lights out for 3 days. I do water changes from LFS with synthetic mix and add RODI daily to top off. RODI also obtained from LFS. Not sure of TDS? What is that?

 

[Bunnee911]

Total dissolved solids. You can get a meter on Amazon. If you don't have a refractometer, get one at the same time.