Two tanks--- both consume different elements

[whiterushen]

Hey all----been running my 2 reef tanks for 3 months now. I'm finally at a good spot where all of my parameters are very consistent and within good tolerances. The interesting thing i have noticed is--- my 24g tank is an LPS tank and my 20g tank is a SPS tank. Whats cool is, the LPS tank seems to be consuming a good amount of Alkalinity---dropping the level from 9 to 8.2 in a weeks worth of time (I'm balancing this by re-addressing my dosage in this tank to keep the ALK level a lot more consisent. In this same tank, CALC is steady at around 435, MAG at 1400 PH 8.0---- i dont add anything to MAG going on 3 weeks and it keeps these levels.
Now my SPS tank, goes through a good amount of MAG. I dose it about 15ml 4x a week to keep the MAG levels steady.
So just wanted to know---does that sound about normal that I have a LPS tank using a decent amount ALK throughout the week while my SPS tank uses a decent amount of MAG?

 

[bertoni]

I've read a number of reports of tanks seeming to consume magnesium. I am not sure what is happening, but I wouldn't worry much. Some organisms, like coralline, can consume a fair chunk of magnesium and alkalinity.

The alkalinity consumption is normal, and that small change (0.8 dKH) corresponds to a change of about 5.5 ppm of calcium, which is well within the noise limits of hobbyist kits. Personally, I wouldn't worry about that, either.

 

[whiterushen]

Much appreciated

Much appreciated

Thank you for the input. I didn't think it was too unusual out of the norm. I just think its interesting since one tank is a SPS and one tank is a LPS---and both are absorbing different elements more than the other.

 

[bertoni]

Maybe we'll learn more in the future, but LPS vs SPS doesn't seem to produce a constant skew. I'm not sure what might be all the factors in this.