Big difference in parameters when testing

Kial · May 23, 2022

homer1475 said:
Reef Chemistry Calculator

Just choose Baking Soda as the additive.

Thanks I'll take a look

homer1475 · May 23, 2022

FWIW.....

If your ALK is actually that low, I would only BOLUS dose up to 7 and not any further.

They say not more then 1dkh per dosage(24 hours), but when your level is that low, it's better to just raise it to 7, then say 6.

gbroadbridge · May 23, 2022

Kial said:
I've just ordered a hannah checker and some alk buffer so I can raise it.

Hopefully be here by the weekend so will test before and after my water change and then use the buffer to raise.

If by the weekend it's even lower, say around 5. What's the safest amount I can bring it up? Would it be too much to raise back to 7.5 which is what it usually is?

I'd suggest 1dkh maximum per day if you don't have sensitive corals. If you do, go slower.

Kial · May 25, 2022

Got my hannah checker today. Just finished the test and it's saying 6.9

The salt mix I use has alk at 7.5 so its not dropping too much really.

My alk buffer product is arriving today so I should be OK to get it back up to 7.5 today

Sean Clark · May 25, 2022

Kial said:
Got my hannah checker today. Just finished the test and it's saying 6.9

The salt mix I use has alk at 7.5 so its not dropping too much really.

My alk buffer product is arriving today so I should be OK to get it back up to 7.5 today

Yes, an adjustment from 6.9 to 7.5 should be fine over one day. I would test a second time with your new Hanna checker just to be sure that your are getting consistent results.

EeyoreIsMySpiritAnimal · May 25, 2022

Please correct me if I'm wrong, but I remember reading that you should wait 12-24 hours after a water change (or dosing) to retest Alk, Ca, and Mg.

Kial · May 25, 2022

Sean Clark said:
Yes, an adjustment from 6.9 to 7.5 should be fine over one day. I would test a second time with your new Hanna checker just to be sure that your are getting consistent results.

Yeah 6.9 on both tests so feel confident it's at that.

Sean Clark · May 25, 2022

Erin1971Texas said:
Please correct me if I'm wrong, but I remember reading that you should wait 12-24 hours after a water change (or dosing) to retest Alk, Ca, and Mg.

Solid advice. No mention of a water change though. Only salt mix.

EeyoreIsMySpiritAnimal · May 25, 2022

Sean Clark said:
Solid advice.

I wasn't offering it as advice, just as what I thought was the correct method. I'm not sure that waiting is necessary though... ?

Sean Clark · May 25, 2022

Erin1971Texas said:
I wasn't offering it as advice, just as what I thought was the correct method. I'm not sure that waiting is necessary though... ?

I don't think that the OP performed a water change. Only that their current water is testing at 6.9 and their salt mix that they use is 7.5 so a presumptive drop through consumption. I have accidentally overdosed alk in the past by not waiting long enough for it to fully mix and stabilize, so I agree that waiting after any change would be ideal.

Kial · May 25, 2022

That 6.9 was a few days after a water change. But to be honest I would usually test 30 mins or so after a water change.

Will definitely wait longer next time though!

EeyoreIsMySpiritAnimal · May 25, 2022

Sean Clark said:
I don't think that the OP performed a water change. Only that their current water is testing at 6.9 and their salt mix that they use is 7.5 so a presumptive drop through consumption. I have accidentally overdosed alk in the past by not waiting long enough for it to fully mix and stabilize, so I agree that waiting after any change would be ideal.

Kial said:
I usually test after my water changes (10% weekly)

This is why I asked my question.

gbroadbridge · May 26, 2022

Erin1971Texas said:
I wasn't offering it as advice, just as what I thought was the correct method. I'm not sure that waiting is necessary though... ?

It's a good idea to simply test at the same time each day.

Not just becuase it gives time for everything to mix and for any chemical reactions that may occur to finalize after a water change but because the values fluctuate quite a lot during a 24 hour period.

I was astonished when I installed an automated Alk tester, just how much the measured Alk varied during a 24 hour period. It may measure 8 dkh at 8am each day but in my tank swung up and down by about 0.4 during the 24 hours when I was measuring every 4 hours. I was able to level it out somewhat by adjusting hourly dose rates, but I'm not sure if that makes a difference to the coral. I've gone back to a single 7am test for my own sanity