How to keep water changes from browning out sps

[kylathwe]

So I have a bit of a dilemma. Still relatively new to sps, I have quite a few frags that are new but have not had to start dosing yet. I'm using an API test kit, I know I need to get a better one. Anyways, my all has been between 8-9 since I got them about a week and a half ago. Most recently was 8 about 3 days ago. I did a small water change of 7 gallons yesterday (first since I got the sps) and my alk shot up to over 10 today.

I use reef crystals and I know it runs high in alk. System is a 90 gallon with 30 gallon sump. How do I keep the alk stable without stopping water changes and strictly dose? Corals have looked fine but started to brown slightly at the base since the water change.

 

[malady]

change to a salt that has the same levels as you want

I had to switch to red sea blue bucket for the same reason

 

[Allmost]

finding a salt with lower KH will cost you more.

so you can just keep your tank KH at 10 Dkh now on. dose to keep stable.

it shouldnt be about 8-9, keep it stable at a number

 

[this is me]

change to a salt that has the same levels as you want

I had to switch to red sea blue bucket for the same reason

Not worth the effort of chasing such salt. Even if you find one, the parameters can change from batch to batch.

Doing a 10% water change every week with salt that has different parameters will not change your parameters much. For example, my 55gal is kept at 9dKH, 450ppm CA, and 1400ppm MG. Doing a 10% water change with Instant Ocean will do the following.

KH=(12x0.1)+(9x0.9)=9.3dKH
CA=(350x0.1)+(450x0.9)=440ppm
MG=(1200x0.1)+(1400x0.9)=1380ppm

Not a significant change and well within the test accuracy of any kit. Not worth the headache of worrying about it. Spend more energy on keeping your parameters stable than chasing the numbers.

 

[kylathwe]

Thanks everyone for the advice, I'm afraid to change salts as I've heard you are bound to lose some corals in the process. I may just have to keep my alk higher. Thanks again.

 

[mayjong]

agreed-
a 7g water change in a 90g system could not have moved alk from 8-9dkh to 10dkh.
a better test kit will give you a more consistant reading...