Alkalinity rising without dosing... possible causes?

[EricR]

Has anyone with a long-term "alkalinity rising with no dosing" identified their problem source and fixed it?
I'm at 8 months of alkalinity rising 0.2 dKH daily and just fighting it off with low alk water changes (using Sodium Bisulfate in new saltwater) every 3 days or so -- works but just inconvenient.

My specifics are that I have all soft corals so could just be due to nitrate consumption but I've also considered replacing my aragonite sand as last ditch effort (but that would be a chore and not confident that's the issue anyway).
*tested all potential sources I could think of (including sand), individually, in small surrogate tank over a couple of months and never found the culprit

 

[Randy Holmes-Farley]

Has anyone with a long-term "alkalinity rising with no dosing" identified their problem source and fixed it?
I'm at 8 months of alkalinity rising 0.2 dKH daily and just fighting it off with low alk water changes (using Sodium Bisulfate in new saltwater) every 3 days or so -- works but just inconvenient.

My specifics are that I have all soft corals so could just be due to nitrate consumption but I've also considered replacing my aragonite sand as last ditch effort (but that would be a chore and not confident that's the issue anyway).
*tested all potential sources I could think of (including sand), individually, in small surrogate tank over a couple of months and never found the culprit

i mentioned this in your other thread, but can you list foods you use?

 

[EricR]

i mentioned this in your other thread, but can you list foods you use?

I mainly feed LRS Reef Frenzy Nano but also, occasionally, feed home-made with MOSTLY chopped, fresh (grocery store) clams/mussels.
Nori and fresh clams for inverts periodically but not massive amounts.
*posted in other thread with additional non-food thoughts also

 

[sgrosenb]

I mainly feed LRS Reef Frenzy Nano but also, occasionally, feed home-made with MOSTLY chopped, fresh (grocery store) clams/mussels.
Nori and fresh clams for inverts periodically but not massive amounts.
*posted in other thread with additional non-food thoughts also

@EricR I dealt with this for a few years. It was highly frustrating. As soon as I removed my sand, the issue went away. That was definitely the culprit. I have enjoyed my bare bottom tank and the lack of maintenance it requires. I do like the look of sand, but I'm all about the corals. My Sps are thriving now for the most part. I would suggest trying removing most of it. I would do it slowly by first agitating some of the sand you wan to remove, wait a few days, then remove that section. Do that process once or twice per week so long as everything looks good. Intermittent water changes throughout the process would help as well.

 

[EricR]

@EricR I dealt with this for a few years. It was highly frustrating. As soon as I removed my sand, the issue went away. That was definitely the culprit. I have enjoyed my bare bottom tank and the lack of maintenance it requires. I do like the look of sand, but I'm all about the corals. My Sps are thriving now for the most part. I would suggest trying removing most of it. I would do it slowly by first agitating some of the sand you wan to remove, wait a few days, then remove that section. Do that process once or twice per week so long as everything looks good. Intermittent water changes throughout the process would help as well.

Thanks for the tip. Sand is one of my suspects even though I tested a fair amount from my DT in a small tank for 3+ weeks with no noted alkalinity rise. (Did that with multiple suspects, individually, over a couple/few months and never figured anything out).

I don't want to go bare bottom but do have replacement sand so will likely start swapping it out at some point. (Just not looking forward to it).

 

[sgrosenb]

@EricR check out posts #34-36 of this thread before you replace the sand. @Randy Holmes-Farley talks through the idea that the ph can be lower in the sand, thus causing the breakdown of the sand and an increase in both alkalinity and calcium. I knew that was my culprit when I put the pieces together - I have lower ph in my tank than most, and I had naturally rising calcium and alkalinity. I took out the sand and it solved my problem in full.

In terms of the test you did with adding sand to a smaller tank - one possibility is that there wasn't enough sand, or it wasn't deep enough, to cause the lower ph in that area, thus the sand didn't break down because there wasn't lower ph / higher acidity. Others like Randy can opine on this better than I can, but that's the first thing that came to my mind.

Mind if I ask why you don't want to go bare bottom? I was in the same boat, with looks and inhabitants as my main reasons for keeping the sand. Ultimately I took it out and donated my blue-spotted jawfish to my LFS. While I miss the BSJ, having a tank with thriving SPS and the bottom filled with LPS causes me to not think twice about sand.

 

[EricR]

@EricR check out posts #34-36 of this thread before you replace the sand. @Randy Holmes-Farley talks through the idea that the ph can be lower in the sand, thus causing the breakdown of the sand and an increase in both alkalinity and calcium. I knew that was my culprit when I put the pieces together - I have lower ph in my tank than most, and I had naturally rising calcium and alkalinity. I took out the sand and it solved my problem in full.

In terms of the test you did with adding sand to a smaller tank - one possibility is that there wasn't enough sand, or it wasn't deep enough, to cause the lower ph in that area, thus the sand didn't break down because there wasn't lower ph / higher acidity. Others like Randy can opine on this better than I can, but that's the first thing that came to my mind.

Mind if I ask why you don't want to go bare bottom? I was in the same boat, with looks and inhabitants as my main reasons for keeping the sand. Ultimately I took it out and donated my blue-spotted jawfish to my LFS. While I miss the BSJ, having a tank with thriving SPS and the bottom filled with LPS causes me to not think twice about sand.

I've read through Randy's articles about low pH areas and effects so agree sand seems like my most likely problem source -- I vacuum a good portion with every water change but there are spots (back corners and under rocks) that I can never get to.

Don't want to go bare bottom because I have/like some inverts that "enjoy" the sand but, also, I just don't really like the aesthetic (without sand) for some reason.

I wish there was some MAGIC "Alkalinity Absorbing" media/device but,,, uhh...

 

[GlassMunky]

I wish there was some MAGIC "Alkalinity Absorbing" media/device but,,, uhh...

a bunch of corals do that lol
Sorry couldn’t help myself

 

[EricR]

a bunch of corals do that lol

Not in my tank -- doh!

In all seriousness, I wish there was a reference for the relative alkalinity uptake for different types of corals.

Other than just guessing that most SPS use more Ca/alk than most LPS that use more than most soft corals, I really have no idea.

 

[Randy Holmes-Farley]

Not in my tank -- doh!

In all seriousness, I wish there was a reference for the relative alkalinity uptake for different types of corals.

Other than just guessing that most SPS use more Ca/alk than most LPS that use more than most soft corals, I really have no idea.

Values vary a lot based on pH and absolute alk values, but most reef tanks will use 0.5 to 3 dKH per day. obviously the amount used by a given small coral is thus small.

 

[EricR]

Values vary a lot based on pH and absolute alk values, but most reef tanks will use 0.5 to 3 dKH per day. obviously the amount used by a given small coral is thus small.

I was thinking along the lines of a metric that estimated uptake of different types relative to each other.

...so, as a completely fabricated example, if I thought acans uptake 3x as much as duncans, I might lean towards adding some acans (or something to that effect).

...just grasping at this point