Chemistry question

[fener103]

Started dosing BRS two part last weekend and had my parameters fairly constant on 11/22. They were as following:

Calcium 440
Alk 8.5 DKH
Mg 1325

Tested with Salifert kits for the Alk and Mg and Elos on the Calcium

Today I tested again having made no additions to the aquarium with chemicals, only top off ro water since last Saturday.

Calcium 440
Alk 4.8 DKH
Mg 1325

System is a Solana with mix softies, SPS and zoos.

Question is should I be using something in my make up ro water to balance before adding to the aquarium? As it seems my alk swung quite a bit this week without anything else barely budging. Thoughts and suggestions are appreciated

 

[ralph atl]

No, you need to add more alk part when dosing. Retest though. If u are using Elos for Alk, it's .5 dkh per drop. Btw.

 

[fener103]

Yes I do check Ph (Salifert) giving me 7.7-8 (not the most accurate I know). So in researching my issue I saw that my Salifert Alk kit would also test freshwater so I checked it on my RO water and it was 1.3 DKH. My thought is this is going to seriously deter my alk from rising even with normal two part dosing if every time I add top off water it will attempt to pull it down. Here's my thought, can I use the Alk portion of the two part to buffer my top off water to 9 without issues? I used the reef calculator on my gallon jug, tested before and after and it raised the level to 9.