Why doesn't my water parameter's change?

[Grey-Skull]

I can't figure it out. I test ever day, my test kits are only 2 weeks old. My parameter's are as follow.
PH 8.0
Alkalinity 11.6
Calcium 425
Magnesium 1395

I have a 72 bow front, 6 months old, 80lbs of live rock several soft corals, 2 clowns, 1 yellow tang , 1 hippo tang, 60 snails, 2 cleaner shrimp.

I'm talking even after a 20 gallon water change, nothing changes.
What's up with that?

 

[Grey-Skull]

I should also add, my nitrites, nitrates, and ammonia, is all 0

 

[Bruno]

what kind of test kits are you using? did they expire?

 

[MikeG]

If you just have soft corals in your tank, you will not see really any changes in the parameters listed as they don't use them in any abundance to grow. If you have not added any suppliments to change these levels then they should be equal to what your fresh mixed salt water is hence no changes in parameters after a water changes. Seems to all make sense to me.

 

[Grey-Skull]

For the PH,Cal,Alk,Mag, I use Salifert
For the Nitrates, Nitrites, & Ammonia is us API
Salifert test kits expire 7/2014

 

[Grey-Skull]

Mike, at the start of my tank and for maybe 4 months old I would have to add cal and mag. I use Bionic 2 part. Alk & Cal and I use Bionic for the Mag too. I understand what your saying about the soft corals, but I thought the live rock would use it up too. I should say also, I'm just start to see spots of cal build up and a coral line. My rock isn't purple, it's green.

 

[MikeG]

I would expect to see negligable changes in levels from things like coraline algae ect. Most likely within testing error unless over a very long period of time.

If you want to verify, take a sample of saltwater and spike it with some baking soda mixed in ro water. This will drive up alkalinity levels and you should see a differenc on your kit.

Likewise, you could make up a batch of saltwater at a lower or higher saliity and it will have a different concentration of calcium and carbonate giving different results.