Old Saltwater

[MotherofDragons]

So about two weeks ago, I mixed a batch of saltwater and used about half of it for my QT tank. Fish is done with quarantine and the remaining 15-20 gallons has been agitating in the Brute unused. I thought maybe I would do a small water change with it today, but I tested again since it had been sitting. The KH is down to 6.6! (My DT is around 8.7) Tested Salinity 1.024 and Ca 420 -so they seem OK. I will probably just throw it out and start new, but I am curious - could I adjust KH with something like baking soda - or maybe something else is going on? Any insights would be appreciated.

 

[Crabs McJones]

I use baking soda to adjust my KH, should be fine. Curious as to why its so low in the first place though...

 

[MotherofDragons]

Thanks Crabs. I dunno why so low. It was 8.8 when I tested it the day after I made it.

 

[mjlash22]

Depending on how large of a water change you plan on doing and how big your DT/system is, shouldn't have much of an impact overall to the KH. Nothing you couldn't supplement in right after the water change.

 

[MotherofDragons]

Depending on how large of a water change your plan on doing and how big your DT/system is, shouldn't have much of an impact overall to the KH. Nothing you couldn't supplement in right after the water change.

Thanks for the input. Probably amounts to 10% change. I usually try to match change water to DT parameters then tweak after change if needed. I just wonder what is going on to reduce KH so much. Is it the long aeration ? And are there things I’m not testing for that could be affected ? I wish I knew these answers. Unfortunately, I was not an A student in chemistry lol!

 

[mjlash22]

I'm no chemistry wiz either, but corals or no corals, without supplements, KH will go down over time whether in a mixing bucket or in the DT. I've just accpeted it and dosed on!