Please help! Way low alkalinity.

dpfish · 2026-09-16T21:37:55-0400

I did some work on my tank equipment about a week ago and must not have got the tube pushed all the way into my doser. I checked alk today and got 3.5 with my hana. Checked it twice. I dose All 4 Reef. I have a 120 gallon display and a 80 gallon frag tank on the same system with a bunch of coral. It went about a week with no A4R. It typically uses 205 ml a day. I have a mixed reef with a lot of high end coral. Looking for advice on how to best bring it back up.

dpfish · 2026-09-16T21:42:17-0400

I also just brought down a lot of corals to add to the tank today. They are still in the bags. I tested the water from them at 7.4 wondering how to get them in the tank? I might need to bring them to a friend's house until I get mine back up

dloberry · 2026-09-16T21:45:56-0400

If you have the option to take them to a friends I would do that to be safe. You will need to bring the alk up slowly. Less than 1ppm per day. Any more will shock them. How are they looking? Closed up? Any polyps bail out?

dpfish · 2026-09-16T21:56:12-0400

Everything works fine. Only reason I checked it was to compare it to the water with my new incoming coral.

dloberry · 2026-09-16T22:00:03-0400

If everything looks good you should be okay to being alk up slowly. But would not shock your other coral by putting them in a tank you know has a low alk. Hope all works out for you

dpfish · 2026-09-16T22:00:36-0400

I guess that's not totally true. I have had a couple of blastos lose a few polyp.

dpfish · 2026-09-17T01:20:21-0400

dloberry said:
If everything looks good you should be okay to being alk up slowly. But would not shock your other coral by putting them in a tank you know has a low alk. Hope all works out for you

Thank you for the replies. I know dosing all for Reef to bring it up is not the correct move. I have the BRS soda ash but I know that raises pH. I also have the aquaphorist part 2 what do you recommend?

Peer.Boerner · 2026-09-17T08:09:29-0400

Baking soda. Use a calculator like this one to determine the dose based on where you are and where you want to be. Dose enough to raise dKh by 1 degree each day, even split the daily dose in 2 to make it gentle.

https://reefapp.net/en/dosing-calculator

Given the urgency you can use plain Arm & Hammer baking soda (sodium bicarb)

Hope all the best for you!

Randy Holmes-Farley · 2026-09-17T08:33:11-0400

I’d be very wary of assuming alk that low is accurate and I’d double check it before making big changes.

dpfish · 2026-09-17T11:12:37-0400

Randy Holmes-Farley said:
I’d be very wary of assuming alk that low is accurate and I’d double check it before making big changes.

I've ran it 3 times with the same reading. I tested the water from the bag the my new coral came in and got 7.4 all with the same tester. I will run it with a different tester today

Randy Holmes-Farley · 2026-09-17T11:15:30-0400

dpfish said:
I've ran it 3 times with the same reading. I tested the water from the bag the my new coral came in and got 7.4 all with the same tester. I will run it with a different tester today

Assuming a second test method confirms the low alk, you have a variety of options to raise it, one of which is just to continue the AFR at the previously OK dose, and a second is to boost with baking soda over a few days while continuing the AFR.

dpfish · 2026-09-17T11:47:10-0400

Randy Holmes-Farley said:
Assuming a second test method confirms the low alk, you have a variety of options to raise it, one of which is just to continue the AFR at the previously OK dose, and a second is to boost with baking soda over a few days while continuing the AFR.

I'm currently dosing brs soda ash because that's what I had last night along with the AFR with the goal of raising 1 dkh every 24 hr. Should I swap the soda ash with baking soda? I'm going to run home during my break to check with a different tester. Would you expect this temporary drop in alk to be harmful for the coral?

Thank you for the all help working me through this!

Randy Holmes-Farley · 2026-09-17T12:18:28-0400

dpfish said:
I'm currently dosing brs soda ash because that's what I had last night along with the AFR with the goal of raising 1 dkh every 24 hr. Should I swap the soda ash with baking soda? I'm going to run home during my break to check with a different tester. Would you expect this temporary drop in alk to be harmful for the coral?

Thank you for the all help working me through this!

The sodium carbonate will boost pH too much to add 1 dKH at once, IMO. I'd go slower with it, maybe 0.3 dKH at a time.

dpfish · 2026-09-17T14:36:57-0400

Randy Holmes-Farley said:
The sodium carbonate will boost pH too much to add 1 dKH at once, IMO. I'd go slower with it, maybe 0.3 dKH at a time.

This afternoon I tested with my hana same one I used yesterday and an aquaphorist test kit that I have. Both tested 4.6 I'm pretty confident that my readings at 3.5 yesterday work correct