Unstable and Low Alk

FishRFriends!=Food · Nov 24, 2023

For the life of me I cannot get a stable Alkalinity. Tested my tank around 1pm, 6.5. Added 25ml of calcium carbonate per BRS recipe, tested again 945pm, 6.0 Alk. Could someone please explain how dosing Alk would cause it to lower?

25 Gallon Lagoon, made no other changes to the tank besides removing maybe 1/20 of a gallon to acclimate a new frag.

TIA

EeyoreIsMySpiritAnimal · Nov 24, 2023

Test error?

Dburr1014 · Nov 24, 2023

Have you tested magnesium?

FishRFriends!=Food · Nov 24, 2023

Dburr1014 said:
Have you tested magnesium?

Tested 1600+ with hanna marine master. Ive tested 4 or so times over the past 2 weeks and mag is always excessively high. The only thing Ive ever dosed besides the cal carb was 1/2 teaspoon of kalk per gallon in my 5 gall ato reservoir for 1 week. Took it out to try and narrow down this issue. Calcium is also reading 600+. Going to verify the results with another brand tomorrow.

SliceGolfer · Nov 24, 2023

Can you clarify what recipe or elements you are using? Calcium Carbonate is usually used in homemade coral snow. Are you using Soda Ash or Sodium Bicarbonate for Alk and Calcium Chloride for Calcium? 1/2 tsp of Kalk per gallon in an ATO isn’t going to add much Alkalinity at all.

VintageReefer · Nov 24, 2023

Try another mag test. The digital ones had a bad production run and read off the charts due to flawed reagents. You might have an earlier model that was leftover

SliceGolfer · Nov 24, 2023

Here’s your example ran through Hazma’s Reef Calculator. I took the liberty to assume your 25g lagoon evaporated 0.5 gallon per day. At 1/2 tsp of Kalk per gallon in your ATO, and 1/2 gallon evap per day, you would add 0.56 dKH.

FishRFriends!=Food · Nov 24, 2023

SliceGolfer said:
Can you clarify what recipe or elements you are using? Calcium Carbonate is usually used in homemade coral snow. Are you using Soda Ash or Sodium Bicarbonate for Alk and Calcium Chloride for Calcium? 1/2 tsp of Kalk per gallon in an ATO isn’t going to add much Alkalinity at all.

Sorry sodium bicarbonate for Alk, I had a drink or two earlier. I havent dosed any calcium by itself short of the small amount of kalk in the ato.

FishRFriends!=Food · Nov 25, 2023

Salifert Alk tested 2 times, 8.0 - 8.3. Hanna Alk, 6.4
Salifert Mag 1450
Salifert Calcium 500+, looks like it was just about to transition, so 525 approx.

Sounds like I should reach out for atleast a replacement on the alk reagents?

vanguard · Nov 25, 2023

I also suspect that the hanna test is inaccurate. I'd give them a call before I used it to chase a number. I wish you had a third test to see which results it matched.

Randy Holmes-Farley · Nov 25, 2023

I don’t which, if either, kit is accurate, but all have some uncertainty, making detection of a small alk change hard to see.

Sodium bicarbonate certainly cannot lower alk. Same for sodium carbonate, but are you sure you did not use sodium carbonate? That’s much more commonly used.

FishRFriends!=Food · Nov 25, 2023

Randy Holmes-Farley said:
I don’t which, if either, kit is accurate, but all have some uncertainty, making detection of a small alk change hard to see.

Sodium bicarbonate certainly cannot lower alk. Same for sodium carbonate, but are you sure you did not use sodium carbonate? That’s much more commonly used.

Hey Randy,

I can confirm that it is sodium bicarbonate. I purchased the BRS 2-Pound Kalkwasser Starter Package, which comes with sodium bicarbonate.

Ordovician_Reef · Nov 25, 2023

Randy Holmes-Farley said:
I don’t which, if either, kit is accurate, but all have some uncertainty, making detection of a small alk change hard to see.

Sodium bicarbonate certainly cannot lower alk. Same for sodium carbonate, but are you sure you did not use sodium carbonate? That’s much more commonly used.

I am curious, how could adding Na Bicarbonate lower ALK ?