Water changes for nano reef

[Jdavis8824]

I've had a IM 20g reef for a year now. I've battled a light brown algea for over 8 months and couldn't seem to find the problem. Eventually I found out it was the salt mix adding silicates into the tank. I did 2 and half gallon water changes weekly and half the time 3-4 gallons to combat the diatoms which was making it worst. My question is how long can I go without water changes? I've recently started with all new life rock about 2 weeks ago and everything seems fine. My rocks are getting covered in diatoms so I don't want to aid them by adding silicates to the water. The rock in the middle of the tank is still really clean. It receives the most light. I have Red Seas ABC elements to dose. My parameters stay at:
Temp 78
Salinity 1.026
Cal 430
Alk 8.4
Mag 1360
Nitrates 0.0
Phosphates 0.0

I have too much filtration and only 3 fish. And 3 small turbo snails.

I also want to add more snails soon. Which are best for diatoms? Turbos stay almost exclusively on the glass

 

[chimmike]

What kind of sand did you use, if any?
Also, what is your water source?

Diatoms tell me that it's silica sand.

have you tried a different salt mix if you think that is the source?

edit: stop dosing elements, especially if you have no way to check them or no way to see what's being consumed and what isn't.

also.....how much flow? IS the rock in the middle getting good flow?

 

[Jdavis8824]

I have Red Sea test kits as well. I just got the elements up just a little and they don't consume much. Can't remember the exact name of the sand but I think it was nutrisea brand. The rock in the middle does get good flow but anymore flow in my tank and my corals don't like it. It's a wave maker. I think the diatoms are there because I changed the rocks completely and the new tank syndrome is starting over again. I know it's the salt because once I stopped doing water changes every week to changing every three weeks, the brown algea started to go away slowly. I just don't want it to happen again.

 

[Jdavis8824]

I get the water from different LFS around my area. I've tested for silicates and they aren't present until after I add the salt.