Why is my alk rising?

[discostew]

Hi I’m 8 months into hobby. In have a mixed reef with fish, softies and lps mainly. 1 or two sps (dead).
I use filtered sea water near by. It’s alk at baseline is 7.4.
I was using all for reef to keep it steady at 8.4 for several months until a battle with Dino’s. I fixed the Dino’s. I have not dose anything for 2 months. My alk is slowly climbing despite weekly 10% water changes.
Current params:
Nitrate 10, phos 0.1, alk 9.7, salinity 1.025, 8.2-8.4. Calc 440 mg 1311.

i have removed the dead sps. I have been lowering my phos down from 0.2 slowly.
Any ideas why my alk is rising?

 

[Reef.]

Are you still using all for reef?

if not then it is probably your top off water, you are probably not topping off enough, also,if you are using floss, or socks, that can slow down the flow or speed it up when you change them, which will also affect the alk if you do not adjust the water lvl correctly to take this into account.

If I was using NSW I wouldn’t be going to the trouble of changing the alk lvl, keeping your tank and the NSW the same alk lvl will make things much easier.

 

[discostew]

Thanks. I haven’t use the all for reef for 2 months because of the alk trend. My ato is a tunze osmolator and i keep the water level constant. I shut the ato off when i adjust the floss or anything that would shift the water level. And I’ve pretty much been using nsw for the last 2 months. The only other thing i add to the tank is fish food and phyto.

 

[LeftyReefer]

If you aren't dosing anything that would raise your ALK, and your ALK is still rising higher than the ALK of your water change water then I'd think its some sort of testing error.

What are you using to test your ALK?

If using a hanna ALk checker, might want to try a new (fresh) bottle of reagent.

 

[discostew]

Ya i did that about 3 weeks ago and it was consistent with the prior bottle. I’ll compare to a Red Sea that i have laying around and try another alk bottle

 

[Reef.]

Ya i did that about 3 weeks ago and it was consistent with the prior bottle. I’ll compare to a Red Sea that i have laying around and try another alk bottle

I just noticed my Hanna read a full 1 dkh high, not sure if it was reading high from new or increased later, I’ve not had it long, I now use Salifert or aquaforest for alk, they are very accurate.

 

[discostew]

I’m regards to the all for reef. I only needed to use 2ml per day to keep the alk stable previously. I found the lps were happier at the all in the 8s rather 7s.

 

[Reef.]

I’m regards to the all for reef. I only needed to use 2ml per day to keep the alk stable previously. I found the lps were happier at the all in the 8s rather 7s.

What size tank?

 

[discostew]

45 gal

 

[Reef.]

45 gal

I think the issue is your testing, sounds to me your numbers just don’t add up, for a 45gal tank, 2ml of AFR would barely register an alk increase on a test kit, I would double check all your testing.

 

[discostew]

Will do. Have some Hannah reagent in order. Will try salifsrt. I just did Red Sea and it’s 9.5-10.

 

[Reef.]

Will do. Have some Hannah reagent in order. Will try salifsrt. I just did Red Sea and it’s 9.5-10.

With Salifert, the instructions show to stop at the pink colour change, don’t, stop before that, the lavender is the correct end point, as soon as the colour changes from blue to lavender that is where to take your reading from.

 

[Randy Holmes-Farley Verified Community Expert]

Rising alk can can from the slow dissolution of rock and sand, combined with very low demand.

Declining or dosing nitrate also boosts alk.

 

[discostew]

Rising alk can can from the slow dissolution of rock and sand, combined with very low demand.

Declining or dosing nitrate also boosts alk.

There is definitely low demand as there aren’t sps to use up as before.

 

[discostew]

Checked on a different Hannah checker, Red Sea and new reagent. And this was after a 15% water change. Still 9.5-9.7. Can’t be the testing across 3 different tests?

 

[Reef.]

Can you post a picture of the tank

What rock and sand did you use?

What corals do you have?

I still am thinking a testing error as my hanna reads a full dkh high so that would put yours at where you were aiming for at around 8.5.

Also what makes me think a testing error is your AFR 2ml dose, the starting dose for your size tank is over 8ml a day, that would only raise alk by under 0.3dkh a day but you were adding only a quarter of that, meaning you were only adding 0.075 alk a day which is next to nothing, so not sure how you got your sea water from 7.4 to 8.5 with 2ml of AFR? your alk would not have moved as even soft corals use more alk than you were adding on a daily basis. Also your water change water is only 7.4 and if your tank really was 8.5 then every time you changed water your alk would be dropping further not increasing.


Never tried Red Sea for alk but I think you read the syringe backwards so easy to make a reading error on that test kit, try Salifert it’s a cheap test, if my tank I would want to make sure of my alk test kit first, to at least cut out that as the cause, easy to make a alk solution to test, you just need some 0.01g scales from Amazon for $20, unless your rock or sand is breaking down I can’t think of another reason not already mentioned.

DIY alkalinity standard

For folks who may want to evaluate the accuracy of their alkalinity test kits, here are two suggested ways to do it. One is DIY and one is a mostly commercial standard with one DIY step. Method 1 Standard solutions could be made with sodium bicarbonate, but it can be hard to be sure it hasn't...

www.reef2reef.com

 

[discostew]

Just an update. Did the Salifert test today 9.3 or 9.4. Hannah and Red Sea are 9.7