Big difference in parameters when testing

[Kial]

Reef Chemistry Calculator

Just choose Baking Soda as the additive.

Thanks I'll take a look

 

[homer1475]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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.

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

This is why I asked my question.

 

[gbroadbridge]

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