Alkalinity going down with AFR

[ReefingIsMyTherapy]

In the last week I've noticed my alkalinity going down even when my AFR dosing has actually increased a bit. Up. Up until last week, I had been dosing 18ml daily which kept my alk pretty stable at 8.3. However, since last week it has been going down and now it's at 8. I know it might not seem like a big swing, but I just can't understand why it's going down. I started dosing 20ml since 3 days ago and it has not increased :/

I don't want to go back to 2 part what are my options? I just tested CA with a RedSea test kit and it came back at 430-440.

If one of the options is to dose soda ash (which I have), how much ahould I wait to dose it after dosing AFR?

Thanks in advance for the help!

 

[undermind]

Well I can think of at least one possible reason - your consumption is increasing?

That certainly is going to be the expectation at some point right? That your corals will grow and you'd need more to keep up?

And then there's the margin of error with your test kit, which 0.3 dkh is probably within.

How long have you been using AFR?

I've been using it for a few years and I adjust my dose frequently. Your Alk reading is just going to vary a little. Time of day, tester margin of error, testing procedures, salinity, consumption, stress events, etc.

None of these things means you need to reach for the soda ash in my opinion. You can certainly adjust the AFR to compensate if you feel you want to take action on a 0.3 movement

 

[Randy Holmes-Farley]

I agree that if you like and want to use AFR, just dose more until alk is stable.

 

[ReefingIsMyTherapy]

Well I can think of at least one possible reason - your consumption is increasing?

That certainly is going to be the expectation at some point right? That your corals will grow and you'd need more to keep up?

And then there's the margin of error with your test kit, which 0.3 dkh is probably within.

How long have you been using AFR?

I've been using it for a few years and I adjust my dose frequently. Your Alk reading is just going to vary a little. Time of day, tester margin of error, testing procedures, salinity, consumption, stress events, etc.

None of these things means you need to reach for the soda ash in my opinion. You can certainly adjust the AFR to compensate if you feel you want to take action on a 0.3 movement

Thanks @undermind I've been using AFR for 2 months. It took me about 2 weeks to fine tune my dosing. I completely agree that coral growth could be the cause of the drop in alkalinity. What I'm finding difficult to understand is why, even after dosing a bit more (2ml in this case) for the last 3 days, I still don't see an upward trend, so maybe I simply need to dose more. I'll keep increasing as per the instructions until I get it back to where I like. My corals are slowly but definitely growing, so I guess that's a good thing.

 

[ReefingIsMyTherapy]

I agree that if you like and want to use AFR, just dose more until alk is stable.

Thanks @Randy Holmes-Farley I like what I've seen so far, so I'll start dosing more until I get my alkalinity stable.

 

[undermind]

Thanks @undermind I've been using AFR for 2 months. It took me about 2 weeks to fine tune my dosing. I completely agree that coral growth could be the cause of the drop in alkalinity. What I'm finding difficult to understand is why, even after dosing a bit more (2ml in this case) for the last 3 days, I still don't see an upward trend, so maybe I simply need to dose more. I'll keep increasing as per the instructions until I get it back to where I like. My corals are slowly but definitely growing, so I guess that's a good thing.

Yeah! Hopefully it is indeed coral growth.

And by the way, just be really patient with making adjustments. I'm sure you're aware of how it takes a while for Alk changes to be seen with AFR, as compared to two part for example. I personally don't like to make bold decisions for at least 3 days after changing a dose. I'm not saying it takes 3 days for changes to be seen, but this is just a general precaution I usually use.

I also think that patience with swings in Alk is a pretty good idea in general too. As I mentioned in my previous post, I find that Alk is just gonna move a bit, and I don't sweat individual movements too much, considering the error margins of tests. I focus on larger general trends: is it moving up, is it moving down? I think that worrying about frequent smaller swings can lead to overcorrections.