Reef crystals crazy alk water changes!

glb · Jun 20, 2015

I've been using IORC for my reef tank for years now. My alk always seems to drop after a 10% water change so I tested the alk in the newly mixed water. It was 2.9kh! How is this even possible? I added some kalk to the new water to bring it up, but now its Ph is 9.0. I only got the alk up to 5.5. What am I to do?? Could my salt mix be too old? I've had it about 12-18 mos. I'm trying to keep things stable but the water changes make my numbers fluctuate more than I'd like. I try to keep the alk around 9kh in the tank. Help!!!

Randy Holmes-Farley · Jun 20, 2015

Kalkwasser isn't a good way to boost alk because the the pH gets too high and that initiates precipitation of more calcium carbonate, lowering alk again.

Are you confident in your kit?

How are you measuring salinity?

glb · Jun 20, 2015

Alk is a Hanna checker and I have a refractometer for salinity. I use a digital handheld Ph monitor. I'm assuming the Hanna is right because the reagent is new. What should I do?

NanaReefer · Jun 20, 2015

Ask for a refund on the salt?! That's crazy! I've been having a different kind of issue with RC. An over abundance of Silicates. Caused me a major Diatom bloom that I'm constantly fighting.

Mandrew · Jun 20, 2015

I've heard it's a good idea
To mix your salt really well before adding it to the water as well because the particles in the salt mix separate. So give it a good stir before use and See if that helps.

Macdaddynick1 · Jun 21, 2015

Use regular IO salt Alk is stable at 9

Downbeach · Jun 21, 2015

Are you sure you aren't reading your alk in meg/l (145 ppm = 2.9 meg/l = 8.12 dKH)? If so, it's still a little low for RC @ a SG of 1.026. Is your refractometer calibrated using a 35 ppt solution?

Righteous · Jun 21, 2015

When I used to use RC I'd inconsistent results a lot. It seems really prone to clumping and settling. Have you tried thoroughly mixing and shaking the salt before making a batch? If you're using the bags, maybe empty it into a bucket and give it a really good shaking and break up any clumps.

Randy Holmes-Farley · Jun 21, 2015

glb said:
Alk is a Hanna checker and I have a refractometer for salinity. I use a digital handheld Ph monitor. I'm assuming the Hanna is right because the reagent is new. What should I do?

I wouldn't rely on the Hanna alk checker to claim that RC has such low alk. I have more confidence in the salt that that the measurement is accurate, especially if you've not used this batch of reagent before. I'd double check with a different method.

Also, how much did you mix up at once? Was it a large portion of the container?

glb · Jun 21, 2015

NanaReefer said:
Ask for a refund on the salt?! That's crazy! I've been having a different kind of issue with RC. An over abundance of Silicates. Caused me a major Diatom bloom that I'm constantly fighting.

Who said anything about a refund for salt??

glb · Jun 21, 2015

Downbeach said:
Are you sure you aren't reading your alk in meg/l (145 ppm = 2.9 meg/l = 8.12 dKH)? If so, it's still a little low for RC @ a SG of 1.026. Is your refractometer calibrated using a 35 ppt solution?

Yes I'm sure I'm measuring it right. I use a Hanna checker in ppm and convert it to kh.

glb · Jun 21, 2015

Macdaddynick1 said:
Use regular IO salt Alk is stable at 9

That would be ideal! I'm almost out so I think I'll try that. What's the difference between the two?

glb · Jun 21, 2015

Righteous said:
When I used to use RC I'd inconsistent results a lot. It seems really prone to clumping and settling. Have you tried thoroughly mixing and shaking the salt before making a batch? If you're using the bags, maybe empty it into a bucket and give it a really good shaking and break up any clumps.

Those are good ideas. I crumble it with my hand as I sprinkle it into the water. I have a bag of rice in with it (in another bag) to keep out the humidity, as I live in south Florida.

glb · Jun 21, 2015

Randy Holmes-Farley said:
I wouldn't rely on the Hanna alk checker to claim that RC has such low alk. I have more confidence in the salt that that the measurement is accurate, especially if you've not used this batch of reagent before. I'd double check with a different method.

Also, how much did you mix up at once? Was it a large portion of the container?

Thanks. The reagent is probably three weeks old which is brand new to me. Since I test alk every day I buy a new bottle every month. But I do have a salifert alk test so I'll check it out. I mix up a gallon at a time because that's all I need for my weekly water change.
As an aside, I tried adding a tbsp of baking soda to raise the alk without raising Ph, and now the alk is over 300. Sigh

Randy Holmes-Farley · Jun 21, 2015

glb said:
Who said anything about a refund for salt??

I think he meant that its crazy the salt is that way, and you should ask for a refund.

However, such events with RC are very rare, and I suspect testing issues over a true bad batch before it is double checked with a titration kit.

Randy Holmes-Farley · Jun 21, 2015

glb said:
Thanks. The reagent is probably three weeks old which is brand new to me. Since I test alk every day I buy a new bottle every month. But I do have a salifert alk test so I'll check it out. I mix up a gallon at a time because that's all I need for my weekly water change.
As an aside, I tried adding a tbsp of baking soda to raise the alk without raising Ph, and now the alk is over 300. Sigh

Oh, the gallon at a time might be the issue. Salt containers can become de-mixed in transit by vibration. The various ingredients have different densities and may settle/rise.

Righteous · Jun 21, 2015

Randy Holmes-Farley said:
Oh, the gallon at a time might be the issue. Salt containers can become de-mixed in transit by vibration. The various ingredients have different densities and may settle/rise.

I was mixing just a gallon as well for my pico when I had consistency issues.

glb · Jun 21, 2015

Well I threw out what I mixed up. I'm going to buy some new salt. Is regular IO better for my circumstances? Do I even need to test alk in my new water?

Randy Holmes-Farley · Jun 21, 2015

I never test alkalinity on new water. I just assume it is acceptable, which for me is a fairly wide range.

I use ordinary IO rather than Reef Crystals since I do not prefer the vitamins and metal chelators that RC adds.

glb · Jun 21, 2015

Randy Holmes-Farley said:
I never test alkalinity on new water. I just assume it is acceptable, which for me is a fairly wide range.

I use ordinary IO rather than Reef Crystals since I do not prefer the vitamins and metal chelators that RC adds.

Thanks. So I made myself crazy for no reason. I'm going to get IO and start fresh. If my alk drops in the tank after the change I'll just dose it up with Kalk.