Ph going up and KH going down What is going on?

Hello reefers,
I started my 120 gallons tank in february of this year. I keep a diary of my params.
Back in april I had a phospate problem and had a red slime problem wich is going away right now with the help of red slime remover,I was using tap water but not anymore.

Other then that everything has been in check until now. and I don't know what is going on.

I have
6 chromis
2 clowns
3 banggai cardinals
1 cleaner shrimp
1 diamond goby
some hermit crabs

90 lbs of dry rock and a few lbs of live rock

My params are

Ph 8.4 (it has been 8.0 since I started so for my tank it's high)
Ammonia 0
NO2 0
NO3 0
Phosphate 0
KH 6 (that's the first time it's that low it's usually 8 )
Calcium is 500 always been on the limit
salanity 1. 025
temp 80


I do 5 gallons water change every week.

So i hope i covered everything that you need to help me.

Thanks

 

Sounds like you simply need to add more buffer (or increase your periodic dosage of such). IMHO a ph of 8.4 is fine.

 

I don't dose and don't understand much about it could you tell me more

 

That's a lot of info for one thread!

Got to the Forums page and look through the water chemistry forum.

 

What method are you using to measure pH? If your using a probe, I'd suggest you clean it and run it through a 2 point calibration check. If your using a test kit, get a new one, run a test with both the new and old kits and compare and post the results...

Seems like you need more buffer since you have dropped from 8 to 6...then again, there's a small chance, it is an issue with the test kit...

 

Hi Marie

I dont see a test result for magnesium there
your calc at 500 - are you dosing calcium in any form ?
if so, its possible that something like the development of coralline algae is using your magnesium which in turn means you dont have a high enough level to support calcium at 500 and maintain a DKH over 7

Steve

 

I don't test for magnesium yet but will get a test for it.
I don't have coralline growing yet but can't wait.
My calcium has always been at 500 don't know why.

I am not sure that I understand what you mean about the coralline algea and calcium Can you explain
Thanks

 

I use API test kit and it's new.

 

I can try

the big 3 in reef keeping are Magnesium, Calcium and Alkalinity

magnesium is the binder - it holds the other 2 elements in solution
if the magnesium is not high enough , typically what can happen is
everytime you increase your calcium level by 20ppm - your DKH can drop by 1 degree
if you then try and increase your DKH by that 1 degree, your calcium can drop by 20ppm

but as your not dosing calcium to maintain that 500ppm and your not having significant coralline growth then this may not be the issue

Steve