Tested my tap water for phosphates today...

[Todd_Sails]

So, I tested my tanks Mg, PO4, NO3, CA2, and KH today.

I got 1500, 0.2, 0.0, 520, 9 respectively.

I had been using tap water for my WC's, but recently got a RO/DI.

My tapwater was 0.5ish, my DI was 0.0

Ive only changed about 40g so far. As I change, as you and I know, it's not a 1:1 Po4 out, 0 po4 in, but it slowly gets dilute to a much lower level, until one day, as long as the food has no phosphates, it will reach zero.

This should help my small amout of cyano, and diatoms more and more each change, right?

[HighlandReefer]

As long as your phosphate level continues to drop after new water change, you will get there. Keep in mind that rock and sand can absorb phosphate and then slowly release it as the water column phosphate level is reduced. So it may take some time.

If the phosphate level climbs or remains steady after water changes, you may need to resort to using a phosphate binding agent like for example GFO. ;)

[HighlandReefer]

"This should help my small amount of cyano, and diatoms more and more each change, right?"

Certainly reducing the phosphate level will help, but not necessarily get rid of cyano in particular. Diatoms will subside as the silicates that were introduced in your tap water decline.

For cyano you will want to keep shallow sand beds cleaned weekly. Remove all debris from the tank & keep the cyano out of your tank. ;)

[Todd_Sails]

I think it's more of a diatom problem, appearling during the day on the CC bed, and almost disappering at night.
It's aslready getting better after only two 15% WC's.

I do now have a shallower bed, 2" or less thru out.

I do try and vacuum tube the bed for a water change usuallly.

I do have lots of LR now, and my chaeto in the sump is growing by the day also.