Alkalinity rising?

[Randy Holmes-Farley Verified Community Expert]

In general, I'd be surprised if that sand was an explanation for rising alkalinity, except perhaps in a tank with very low natural demand for alkalinity. Sand dissolution is a slow process.

 

[sgrosenb]

In general, I'd be surprised if that sand was an explanation for rising alkalinity, except perhaps in a tank with very low natural demand for alkalinity. Sand dissolution is a slow process.

@Randy Holmes-Farley thanks as always for your insight. You had posted this handy list of possible alkalinity rising culprits:

Test error,
top off with tap water,
decline in nitrate,
dosing of nitrate,
dissolution of new artificial live rock
supplements or foods that contain alkalinity even if you do not realize it
dissolution of live rock or sand due to very low tank water pH
dissolution of live rock or sand due to very low pH inside of them due to degradation of organics

If we operate under the assumption it is not test error (which I understand is a big assumption), and we doubt that it is really just the sand that is the reason, any thoughts on what the most likely culprit is? I can say for me, top off is not tap water, I don't dose nitrate, and my nitrate stays rock steady at 8ppm. That would leave rock or food... I guess if it is rock, the only way to find out is to pull it from the tank. For food, I have solely used PE pellets and PE mysis shrimp for the life of the tank.

 

[Randy Holmes-Farley Verified Community Expert]

Fake rock made from cement is the biggest known culprit for rising alkalinity and pH. It needs a long time of curing. one guys selling it years ago aged it in his local creek for months before selling it. Maybe it was GARF.

 

[sgrosenb]

@hobbyreefer @sgrosenb I was going to wait a bit more to post this, but after months of Alkalinity rising with no solution I couldn't wait! On April 29th in the evening I took out 85% of my sand and the rest the next day. As you can see by the chart my Alkalinity has stayed stable and has even declined from the time I took out the sand! The huge drop in Alkalinity is because the day I took out the sand I did a big water change using water that I added muriatic acid to.

I will keep this thread updated as more time goes by, but initial results are very promising. Now the question is why would the sand be the cause of rising Alkalinity?

@eshtog just curious if you're still seeing maintained alkalinity over the past few days?

 

[eshtog]

@eshtog just curious if you're still seeing maintained alkalinity over the past few days?

Yes, alkalinity has been steady and I have started dosing again to bring it up to around 8. If I still had the sand I would be back at 8 by now if not higher. Also, all my corals look so much better then before!

 

[sgrosenb]

hey @hobbyreefer @eshtog sorry to keep asking but just wanted to check and see if your alkalinity issue is still solved after taking out sand? I'm going to take it out this weekend but want to be doubly sure it will be for a good cause! Thanks!

 

[hobbyreefer]

Yes removing the sand appears to have fixed my issues. My alkalinity now stays stable at 7.5 exactly where I want it. I removed all of my sand at one time but my tank is only around six months old. I did a couple of large water changes after removing the sand. I can notice a significant improvement in my coloration and PE over the last three weeks. This was low risk for me because my tank was new and not doing great. I would be a lot more nervous on an established tank.

 

[Randy Holmes-Farley Verified Community Expert]

I'm glad everything is working out!

 

[eshtog]

hey @hobbyreefer @eshtog sorry to keep asking but just wanted to check and see if your alkalinity issue is still solved after taking out sand? I'm going to take it out this weekend but want to be doubly sure it will be for a good cause! Thanks!

Unlike @hobbyreefer my tank is over 2 years old. My alkalinity is still stable. I started dosing to bring it up to 8 and now it’s staying stable at 8 even with continued dosing. My corals have also never looked better!

 

[sgrosenb]

Unlike @hobbyreefer my tank is over 2 years old. My alkalinity is still stable. I started dosing to bring it up to 8 and now it’s staying stable at 8 even with continued dosing. My corals have also never looked better!

@hobbyreefer @eshtog I removed about 1/3 of my sand and began to see a small spike in alkalinity (went from 9.2 to 9.9 over a day or two). This isn't uncommon when I do a water change - even though the fresh salt water that I'm adding is 7.5-8.0 dKH. But I haven't seen it start to come down yet. Did you both see a small spike before you fully removed the sand? I'm going to remove another 1/3 today most likely. Thanks for your insight!

 

[hobbyreefer]

No, I did not see any DKH increases while removing my sand. I performed 2 large water changes (40%-ish) over a 2 day period and my DKH went from ~8.9 to ~7.9. I've now let it drop to about 7.5 and it's remaining steady. I'm dosing ~ 40 ML of soda ash daily to keep it here. It's been several weeks since I've pulled the sand and my DKH has been very stable.

 

[eshtog]

@hobbyreefer @eshtog I removed about 1/3 of my sand and began to see a small spike in alkalinity (went from 9.2 to 9.9 over a day or two). This isn't uncommon when I do a water change - even though the fresh salt water that I'm adding is 7.5-8.0 dKH. But I haven't seen it start to come down yet. Did you both see a small spike before you fully removed the sand? I'm going to remove another 1/3 today most likely. Thanks for your insight!

I didn’t have a spike either but I also almost took out all my sand in one day and did a large water change.

 

[sgrosenb]

Just an update for anyone following along... Unfortunately I'm not having as much success as @eshtog and @hobbyreefer I've taken out about 75% of my sand and my alkalinity continues to rise. I'll give it another week or two, but at this point my only real option left is to change out the rock. I have reef saver rock form Aquacave https://www.aquacave.com/reef-saver-dry-aquarium-live-rock.html. I'm going to switch it out with live rock from KP Aquatics. I'll update everyone as I go... so bummed that the sand doesn't seem to have fixed it yet!

 

[Randy Holmes-Farley Verified Community Expert]

Just an update for anyone following along... Unfortunately I'm not having as much success as @eshtog and @hobbyreefer I've taken out about 75% of my sand and my alkalinity continues to rise. I'll give it another week or two, but at this point my only real option left is to change out the rock. I have reef saver rock form Aquacave https://www.aquacave.com/reef-saver-dry-aquarium-live-rock.html. I'm going to switch it out with live rock from KP Aquatics. I'll update everyone as I go... so bummed that the sand doesn't seem to have fixed it yet!

Thanks for the update!

You think its better to change rock than lower alk by water change?

 

[sgrosenb]

Thanks for the update!

You think its better to change rock than lower alk by water change?

Good question Randy - I'm not sure. I do 10% water changes and I can't seem to get my alk down below 9 dKH with my weekly WC's; the alk rise is too quick for me to keep up. I've tried acid buffer as well but it lowers my pH too far with minimal dKH decline. Also - I started with all dead rock, so I'm actually looking forward to getting live rock in there. what do you think?

 

[Randy Holmes-Farley Verified Community Expert]

Good question Randy - I'm not sure. I do 10% water changes and I can't seem to get my alk down below 9 dKH with my weekly WC's; the alk rise is too quick for me to keep up. I've tried acid buffer as well but it lowers my pH too far with minimal dKH decline. Also - I started with all dead rock, so I'm actually looking forward to getting live rock in there. what do you think?

Yes, you need special water for this purpose. A rock change is huge, and making 1 dKH new salt water is relatively easy.

I discuss how to lower alkalinity in these threads. Do it in the water change water:

Sodium Bisulfate to Reduce Alkalinity in New Salt Water or in Display Tanks
https://www.reef2reef.com/threads/s...in-new-salt-water-or-in-display-tanks.362825/

Reducing alkalinity ?
https://www.reef2reef.com/threads/reducing-alkalinity.339109/#post-4214464

 

[sgrosenb]

Yes, you need special water for this purpose. A rock change is huge, and making 1 dKH new salt water is relatively easy.

I discuss how to lower alkalinity in these threads. Do it in the water change water:

Sodium Bisulfate to Reduce Alkalinity in New Salt Water or in Display Tanks
https://www.reef2reef.com/threads/s...in-new-salt-water-or-in-display-tanks.362825/

Reducing alkalinity ?
https://www.reef2reef.com/threads/reducing-alkalinity.339109/#post-4214464

very interesting- this is awesome. I'll take a read. so you're saying that replacement water that has an extremely low dKH isnt harmful? that's great news

 

[Randy Holmes-Farley Verified Community Expert]

very interesting- this is awesome. I'll take a read. so you're saying that replacement water that has an extremely low dKH isnt harmful? that's great news

It isn't harmful as long as you aerate it so the pH isn't super low, and do not drop alk too much at once in the main tank. If you do a 10% change, you could drop alk by 0.5-1 dKH, which is OK.

 

[sgrosenb]

Yes, you need special water for this purpose. A rock change is huge, and making 1 dKH new salt water is relatively easy.

I discuss how to lower alkalinity in these threads. Do it in the water change water:

Sodium Bisulfate to Reduce Alkalinity in New Salt Water or in Display Tanks
https://www.reef2reef.com/threads/s...in-new-salt-water-or-in-display-tanks.362825/

Reducing alkalinity ?
https://www.reef2reef.com/threads/reducing-alkalinity.339109/#post-4214464

Great - so just for avoidance of doubt @Randy Holmes-Farley , you're saying that my new, mixed saltwater can have a 1.0 dKH, so long as I aerate it to bring pH back up? Like you're saying, a 10% WC with 1dKH water on a tank that has 10dKH could bring it down almost to 9dKH? That'd be awesome if it is indeed safe to do.

 

[eshtog]

Great - so just for avoidance of doubt @Randy Holmes-Farley , you're saying that my new, mixed saltwater can have a 1.0 dKH, so long as I aerate it to bring pH back up? Like you're saying, a 10% WC with 1dKH water on a tank that has 10dKH could bring it down almost to 9dKH? That'd be awesome if it is indeed safe to do.

This is what I did to get my Alkalinity down when I did a water change and removed my sand. I had no problems.