Freshly mixed IO salt measures at 2dkh (?)

[reefsmurf]

Just mixed some instant ocean water up, got it to the right salinity and temperature. Then for kicks I measured the alkalinity and it was 2 dkh

The dkh in my tank is 5, so now maybe I know why...

The salt's pretty old. I have a new box of salt lying around that I'm going to use to see how it differs, but just thought I'd post to see if anyone else measured their freshly mixed saltwater's alkalinity.

 

[stingythingy45]

That's odd.
Wonder if some of the different elements in the mix can seperate over time?

 

[MikeG]

Was the salt clumped or hard?

 

[reefsmurf]

Some of it was clumped and some of it was loose. Does this mean you can't use partially clumpy/hardened salt?

 

[MikeG]

Some of it was clumped and some of it was loose. Does this mean you can't use partially clumpy/hardened salt?

Sometimes salt that is hard or clumped has had moisture get into it and can form a calcium carbonate precipitate. This normally won't go back into solution and would result in low test results of both. This is going from memory so I could be a bit off.

 

[reefsmurf]

That makes sense. But the mystery continues:

I opened a plastic sealed 5gallon minibox of IO salt and it's been mixing for a few hours.
Here are the measured parameters:

Salinity: 1.026 (refractometer and swing arm verified)
Temp: 79 degrees F (triple verified)
pH: 9.55 (recalibrated Pinpoint probe. my own tank water is 8.45, and water I received from a reef member today is 8.3)
Alk: 4dkh (tropic marin test, verified to be close to my Salifert)

Ok, so that's slightly better than the 2-3dkh on the "old salt" but still way off the recommended 8-10. The old salt is reading 8.8pH versus this, a whopping 9.55 pH.

Even assuming the pH will level off overnight, why is the alkalinity so low? This makes not me want to do any water changes

 

[Moe_K]

The solution to pollution is dilution. Water changes are a necessary evil (yeah, I know, I'm a slacker).
Besides, baking soda and Dowflake are cheap.

 

[reefsmurf]

So do you guys actually mess around with your water before adding it? I can't see how it's safe to do water changes if your new water parameters are *that* off...

 

[Moe_K]

Yeah, I add baking soda solution and later a Dowflake solution.

 

[MikeG]

I have yet to see a fresh batch of IO to measure like that, Mine has always had an alk of about 10 and a calcium of about 320-350ppm. I do adjust calcium of fresh made salt water but alk is always on the high end.

 

[reefsmurf]

Thanks for the tip Moe. Luckily I have both.. more work to do *grumble*

Mike: Hrm.. well I have an unopened bucket of IO as well. How many 5g buckets of unuseable salt water can a 29g need