I started a new 120g FOWLR 2 weeks ago. My tap water TDS is 50 ppm, RODI water is 0. I've tested the TDS in the aquarium several times over the last few days and it's 5,000-6,000! I'm using the AquaFX TDS Meter. For some reason I can't find a normal range standard for water actually IN the aquarium.

Is this high TDS in the aquarium a problem? I do have a diatom/brown algae issue for the first time ever, but I'm reading that that is common in a new FOWLR (but it never happened to me before). I'm running a Fluval FX-5 right now and just added a ****-ton of Phosguard to it last night (that's all that's in it media-wise right now, aside from some dry rock scraps).

Should I be concerned about the high TDS? Will lowering the TDS help get rid of the diatoms/brown algae?

Ammonia and Nitrite are 0, Nitrate is 20.

(PS - Not to be a *****, but I already know that I need to watch out for nitrate breakthrough from the canister hahaha!)