What is Causing My Alkalinity to Drop?

[IndyReef78]

I'm still battling a major issue with dinos (added a UV sterilizer to the mix last night). When I tested this morning, my alkalinity had dropped from 8.3 to 4.3 in less than 4 days. I only have a few small soft coral frags in the tank. What is causing that sudden drop? I did mix some baking soda with tank water and have started trying to raise the level again, but I guess I don't understand why I'm having such a hard time stabilizing the alkalinity. Any thoughts?

 

[Sophie"s mom]

We will need a lot of info on the tank. How old is it? Size? Inhabitants? Parameters.

 

[piranhaman00]

4.3 is testing error, not possible

 

[Sophie"s mom]

I'm still battling a major issue with dinos (added a UV sterilizer to the mix last night). When I tested this morning, my alkalinity had dropped from 8.3 to 4.3 in less than 4 days. I only have a few small soft coral frags in the tank. What is causing that sudden drop? I did mix some baking soda with tank water and have started trying to raise the level again, but I guess I don't understand why I'm having such a hard time stabilizing the alkalinity. Any thoughts?

What test kit are you using?

 

[DanyL]

4.3 is testing error, not possible

I mean, it is possible.
Just unlikely in a tank with low to non existing consumption.

 

[IndyReef78]

So the tank is about 3-4 months old, fully cycled, 210-gallon display with a 40-gallon sump. There are about 12 fish, the largest of which is a 3.5-inch anthias. There are maybe 6-8 coral frags - frogspawn, hammer, two tiny torches, a small frag of zoas, and two other SPS corals of some sort that I can't remember. I am using a month-old Hanna Alkalinity tester that has been very consistent. When I first tested with it, it also gave me a very low 4.something reading and I had to dose to get the alkalinity up. Parameters are listed below:

DATE	ALKALINITY	CALCIUM	MAGNESIUM	PH	PHOSPHATES	NITRATES	COMMENTS
7/7/2024	9.8	350	990	8.2	0.25	0	Dosed Reef Fusion 1&2, Magnesium, 25 ml H2O2, turned lights to 5% blue to get rid of dinos
7/8/2024	9.7	365	1140				Dosed H202 and turned off reef mat and skimmer in evening
7/9/2024	9.8	365	1140	8.2	0.25	0	Dosed H202
7/10/2024							Dosed Reef Fusion 1&2, Added Galaxy pods
7/11/2024	9.8	370	1140	8.4	0.25	0	Dosed Chemi Clean, Magnesium, Added Poseidon's Feast Pods and Clean up crew
7/12/2024	9.8	370	1140	8.2	0.4	1	Lights out all day
7/15/2024				8.2	0.3	7	Dosed NeoNitro in morning, turned skimmer back on at 15% in evening
7/16/2024	9.4	340	1130	8.2	0.3	7	Turned lights back on, still red stringy stuff on sand, cheato sort of disintigrating
7/17/2024	9.4	340	1130	8.2	0.3	7	Turned off skimmer in evening
7/18/2024						5	Added dose of NeoNitro, added Magnesium and half dose of Eco Balance, Manual Dino Removal
7/19/2024	8.6		1110	8.4		10	Added Magnesium,
7/22/2024	8.3	350	1050		0.25	7	Added NeoNitro
7/23/2024				8.5		5	Added NeoNitro, Reef Fusion 1 & 2
7/25/2024							Installed UV Sterilizer (started late in the evening) Ran Reef Mat for around 12 hours
7/26/2024	4.3	360	1070	8.2	0.25	5	Lights out all day, added NeoNitro, Baking soda mix, Reef Fusion 1&2

 

[Miami Reef]

What does the alkalinity test in new saltwater? If it’s testing within range of the salt specifications, then you can assume the tester is accurate.

Fortunately, it’s very easy to add alkalinity.

This calculator is very helpful: https://www.bulkreefsupply.com/reef-calculator/alkalinity-calculator-reef

 

[IndyReef78]

What does the alkalinity test in new saltwater? If it’s testing within range of the salt specifications, then you can assume the tester is accurate.

Fortunately, it’s very easy to add alkalinity.

This calculator is very helpful: https://www.bulkreefsupply.com/reef-calculator/alkalinity-calculator-reef

I don't have any new saltwater made at the moment because we are limiting water changes to try to get the nitrates up.
I am using that calculator to help raise the alkalinity. Thank you for the link!