Ph swings and RTN

I can't seem to keep my Ph stable. At night it drops to around 8.30 and during the day it rises to 8.50ish. I lost a sps frag last week to RTN and I now notice a mille with RTN. Could the Ph swing be causing this? I checked my parameters last week and everything was fine except my Cal us up to 500. The only other thing I can think of is I'm a week late for changing out my carbon.

Any advice on the Ph swings and RTN will be helpful.

 

It is possible since the pH gets to 8.5 during the day.

Please list your alk, mg and salinity values also as each of these can play a role also.

Definitely let your Ca drop to 380ppm to 450ppm.

 

Are you dosing anything?

The pH swing values you posted are not really dramatic, perhaps if some other stressor is going on it may be a contributing factor to RTN, like an elevated Ca level.
If possible please provide a Alk and Magnesium level as well.

Newer carbon would increase the risk of RTN in my opinion.The old carbon is a biological filter now. Adding a large amount of new carbon to an existing tank can be problematic in it's own right. Unless you feel the carbon is removing some toxin in your tank other than the routine DOC I would not think old carbon would contribute to RTN.

 

I will check my CAl, Alk and Mag when I get home from work. A week ago when my cal was 500 by alk was 7.5, didn't check my mag. My salinity has been a bit low so I've been doing small water changes trying to get it up from 1.022.

I was mixing 2 teaspoons of kalk to 5 gallons of ATO water, but I stopped that a couple weeks ago since my Calcium was so high and my Ph was getting so high.

 

The RTN sounds like a combination of things with all of your parameters being all over the place.

How were you introducing the kalk?

 

mixing it in my ATO water.

 

Good it is diluted as it goes in.

 

I concur with what 2in10 has stated. seems like alot of swinging in several areas. In my opinion, your CA and PH are too high and your ALK is too low. your salinity needs to be boosted up too. FWIW, you can go up .03 per day without any ill effects on fish and inverts from my experience. Lower alkalinity can lead to PH swings. use some Baking soda to gradually boost that up over the next few days to get it around 8 or 9. I say baking soda because the pickling lime will also raise the CA. Do this slowly because it will raise the PH a bit. once you get the alkalinity stabilized, it should work to keep the rest in line for the most part.

Overall, I only monitor my PH for rapid swings. that is usually a sign of an underlying problem somewhere else. Most tanks are in teh 7.8-8.2 PH range. over the last 10 days mine runs from 8.14 to 8.08.

 

Also, I tested my alk and cal with Hanna testers so I'm assume they are accurate.

 

Parameters are as follows:

Alk - 7.5 dkH
Mag - 1480-1500
Cal - 580 first test. 600 second test

Salinity 1.023

pH at 8am: 8.29
pH at 12pm: 8.33

Temp at 8am: 79
Temp at 12pm: 80

Looks like calcium may be my problem. I changed my ATO water to plain RODI no kalk. I'm also mixing 10 gals to do a water change this evening when I get back home to raise my salinity and hopefully reduce my calcium level.