How to tell if my alkalinity dosing is Precipitating

goose0211

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Hi all,

Am struggling to get my alkalinity levels back up. Been running at 8dkh for ages but recently they’ve been dropping and am having to supplement dose and increase daily dosing yet they’re still not increasing.
Currently they’re at about 4.5 and am beginning to wonder if the dosing isn’t working and the alkalinity is precipitating out - assuming that’s possible?

Ive a mainly SPS tank, though in no way over run or over loaded in a reefer 250 and dose Red Sea Foundation B liquid. Have been dosing approx 35ml a day and kept my levels stable but recently have had to supplement 40 or 60 ml a day to bring levels up yet measure each day or every few days and the levels are about the same.

Any thoughts, should I stop dosing for a few days and re measure the uptake or how can I tell if precipitation is happening?
 
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goose0211

goose0211

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Thanks, I’ve always struggled with Mag readings as they always show very high so tend to not bother (maybe wrongly).
I assume an elevated or low Mag reading will cause problems with alk dosing?
 
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goose0211

goose0211

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Just re tested my mag and it’s around 1500 - presumably a little high assuming the test kit is right?
 

Randy Holmes-Farley

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How much alk are you adding in dKH per day?

Is the sand hardening or do you see apparent deposited precipitate? (the initial cloud on dosing is normal).
 
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goose0211

goose0211

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How much alk are you adding in dKH per day?

Is the sand hardening or do you see apparent deposited precipitate? (the initial cloud on dosing is normal).
I’m dosing approx 0.5dkh but recently having to supplement an addition 0.5 as levels were dropping.

Sand bed is fine, not crusty and no additional sign of precipitate.

lve just measured dkh after 24 hours of no dosing and the levels are the same as yesterday…so that’s confused me??
 

schuby

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Additives we dose to maintain Ca and Alk (I use ESV B-ionic 2-part) don't work well to adjust the overall levels. When I need to raise Ca or raise Alk, I use a targeted booster product and not more of my 2-part, being careful not to exceed the max dosage per day.

If your Ca and Alk isn't precipitating, then that means your tank is using more and corals are growing!
 
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goose0211

goose0211

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If your Ca and Alk isn't precipitating, then that means your tank is using more and corals are growing!
Corals are doing pretty well and show no signs of suffering under such low (4.5dkh) levels - except one plate coral.

Why though would my levels be the same as yesterday having not dosed anything?
 

Randy Holmes-Farley

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Corals are doing pretty well and show no signs of suffering under such low (4.5dkh) levels - except one plate coral.

Why though would my levels be the same as yesterday having not dosed anything?

Once the alk gets to that level, it is much harder for organisms to use it, and abiotic precipitation will stop unless the pH is very high.

I'd also be very sure you are doing the test right. That is very low. So low that I'm surprised you got there.

What does this test say on new salt water?
 
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goose0211

goose0211

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Once the alk gets to that level, it is much harder for organisms to use it, and abiotic precipitation will stop unless the pH is very high.

I'd also be very sure you are doing the test right. That is very low. So low that I'm surprised you got there.

What does this test say on new salt water?
Thanks @Randy Holmes-Farley

I'm using a Salifert Alk test kit and have also backed that up with a Hannah check and both are the same to within 0.2dkh of each other.

New Salt water shows what the bucket says - in my case Red Sea Coral Pro at about 11.
 

Randy Holmes-Farley

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Thanks @Randy Holmes-Farley

I'm using a Salifert Alk test kit and have also backed that up with a Hannah check and both are the same to within 0.2dkh of each other.

New Salt water shows what the bucket says - in my case Red Sea Coral Pro at about 11.

OK, then I'd raise it at least 0.5 dKH per day until you get to 6.5 dKH, then maybe slow the rise a bit.

4.5 dKH is quite stressful for calcifying organisms.
 
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