Alkalinity Rising - No dosing

[Gone Reefin’]

Hey all. Not a newbie but I have an odd issue. I’ve seen several posts on this but unfortunately none have had resolution. My alkalinity is rising without cause…

I am up to 11.2 tonight. It rises 0.3 units every week. At first, I thought it was because my salinity was slowly rising (up 0.001 over last month). So I started doing my AWC with 1.008 water for last week (about 3% WC overall). It keeps rising.

Ruling out testing error as I use same test and protocol on my reef tank, steady as a rock there. Ruling out salt as I use an 8dkh salt (AF hybrid) and I use in both tanks. Ruling out rock as it is all live rock from GLR and TB salt. The only thing I have left is my substrate. I am using crushed coral from Caribsea. Is it possible this is dissolving?? Tank has been up 6 months and alk increase only started 6 weeks ago. I actually had to dose a little AFR early on as my dkh was 7. I stopped dosing two months ago when I hit 9 and it has kept rising since. montis started struggling and bleaching at 10.3, now torches are struggling at 11.2. Tonight I am doing a 5% WC with near freshwater. I am not sure where to go next. Thoughts?

 

[unchainedcoot]

Hey all. Not a newbie but I have an odd issue. I’ve seen several posts on this but unfortunately none have had resolution. My alkalinity is rising without cause…

I am up to 11.2 tonight. It rises 0.3 units every week. At first, I thought it was because my salinity was slowly rising (up 0.001 over last month). So I started doing my AWC with 1.008 water for last week (about 3% WC overall). It keeps rising.

Ruling out testing error as I use same test and protocol on my reef tank, steady as a rock there. Ruling out salt as I use an 8dkh salt (AF hybrid) and I use in both tanks. Ruling out rock as it is all live rock from GLR and TB salt. The only thing I have left is my substrate. I am using crushed coral from Caribsea. Is it possible this is dissolving?? Tank has been up 6 months and alk increase only started 6 weeks ago. I actually had to dose a little AFR early on as my dkh was 7. I stopped dosing two months ago when I hit 9 and it has kept rising since. montis started struggling and bleaching at 10.3, now torches are struggling at 11.2. Tonight I am doing a 5% WC with near freshwater. I am not sure where to go next. Thoughts?

I’d check my RO

 

[Gone Reefin’]

RO as in check alk of water out of it?

 

[Randy Holmes-Farley]

Calcium carbonate rock and sand does dissolve slowly, and thus when demand is very low, alk can slowly rise.

Falling or dosing nitrate also boosts alk, as can some additives that may not mention it.

Tap water can add alk, but ro/di won’t.

Water changes with very low alk (you can make it as low as you want) may be the best bet, though direct acid addition can be done extremely slowly, if you want to lower alk.

 

[Gone Reefin’]

Thanks Randy. I’ve read your posts on bisulfate. If I go this route (thinking seachem until I can acquire some Loudwolf), how long should I aerate/mix saltwater after adding the acid and before adding to tank? I’d rather go this route to avoid tanking pH.

Also, what are yours and other thoughts on a 2 dkh increase over 2 months up to a level of 11 being detrimental to SPS? Trying to determine if this is my root cause or if something else is likely at play.

 

[Randy Holmes-Farley]

I’ve not heard of any issues at 11 dKH as long as nutrients are not too low.

Are you able to measure pH in the new salt water?

 

[Gone Reefin’]

Not reliably. I have a Red Sea test kit for pH but no probes or meters that are free.

 

[Randy Holmes-Farley]

Without a pH meter, I’d aerate the new salt water heavily for 24 h. :)