Does algae effect Kh parameters?

[Michelesreef]

I recently divided a 14 gallon tank into two 10 gallon tanks. I did this for a few reasons. Reason one, I decided to start propagating my hundred of mushroom corals. The 14 gallon tank had a small surface area due to it's height. The two 10 gallons are much shorter, almost like frag tanks. I also needed more surface area to put the new corals. I started both 10 gallons up at the same time. I used 50% of the water from the original tank, along with 50% new saltwater. I have been monitoring the parameters and all seems good. Calcium and Mag are at great levels. I keep the salinity a tad higher, along with the temperature, due to the absence of fish. In fact, when the house gets a little warmer, the corals seem to thrive when the temperature gets up to 80. The only issue I see is with my Kh between the two tanks. One tank has a Kh of 8.3, while the other about 7.2. This is only after a month of setting up these tanks. Everything that I have done to one tank, I did the same to the other.
The tank with the LOWER Kh has more frags with a ton of hair algae on them. The other tank has frags with much less. As I am working on controlling the algae (the algae came from the original tank) I cant help to wonder why there is such a drastic change in Kh between the two? The one with the hair algae did have a few more corals in it at first, but now they have about the same!

Any insight as to the presence of algae creating a lower Kh? I have googled for hours and really cannot find an answer! Thanks for your time guys, and gals!

 

[Randy Holmes-Farley Verified Community Expert]

Noncalcerous algae does not consume alkalinity. Calcaerous algae such as halimeda or coralline certainly can.

The difference is very VERY small, if you are not dosing. 1 dKH difference in a month? 0.03 dKH per day difference. A little more growth in one tank would do that ten times over.