pH\salt mix problems

[M.Maddox]

I aerate\heat my mix water for several hours, and bring it up to a pH of 8.4 using a kalk drip. However, whenever I add Instant Ocean to the water (for an SG of ~1.025), the pH drops to 8, and DOES NOT stay above that, no matter how much kalk I drip. I can drip a mixture containing 1\2 tsp into 12 gallons of mix, and the ph rises to 8.3, but then falls again back to 8.0, even with agressive aeration and the windows open, and after 24 hours it's down to 7.7. Argh!

I've tried 3 different batches of IO - never had this problem before until the last 2 months.

Any ideas? Thanks!

 

[MikeS]

what does the pH of your mix do if you don't aerate it?

MikeS

 

[wrightme43]

Never experinced it myself. I use I.O. and consistently get 8.3-8.4 ph. Let me ask you this. Are you getting any preciepitaion of calcium carbonate in your mixing container. I added accidently before I knew better too much buffer to fresh saltwater. (it seemed like a good idea at the time) LOL I had a snowstorm in my mix bucket and the ph dropped severly. What type of test kit are you using? Just cause I wonder. What type of refractometer or hydrometer are you using? Just asking so everybody knows where your at. Sorry I am not more help on this one. I will keep thinking on it. Steve

 

[M.Maddox]

I use tapwater (been using tapwater for 11 years now) and it comes out of the faucet @ a pH of 8.1, 120ppm calc, and about 9 dkh alk. I'm using a pinpoint meter for pH testing. I buffer the water to 8.4 with a slow kalk drip (to avoid any precipitations) before adding the salt.

I've had marine aquariums for quite a while, and mixed a bunch of salt, but this one has me stumped :\.

Oh, I also tried RO and distilled water, same problem...

 

[wrightme43]

My apoligizes, its hard to tell what people know without asking them. That is very odd to me, I have never had that problem. I wish I could give a idea, but I just dont have one. Steve

 

[M.Maddox]

No problem, and join the club! ><

 

[MikeS]

I use tapwater (been using tapwater for 11 years now) and it comes out of the faucet @ a pH of 8.1, 120ppm calc, and about 9 dkh alk. :

hmmm...I wonder if the imbalance there could be part of the problem....

MikeS

 

[fishdude]

Just read this thread hoping to get some info on pH levels. From what I read above is 8.4 the optimum level for a reef tank? I know this may sound like a dumb question but I am just starting my first saltwater tank and need to learn this sort of info.
Thankyou in advance for your help

 

[fishdude]

Don't worry about answering that I have looked it up myself thanks

 

[Scooterman]

Strange situation for sure, I must admit, I don't think a PH of 8 is all that bad though adding chemicals just to raise the PH may lead to other problems, is everything else balanced after adding the IO because I'm sure adding IO will jump your levels CA, MG, ALK, ST? I do agree I would like to know what is going on to cause this, this may be a question for Boomer or one of the other experts.

I know you may have this but just in case,http://home.comcast.net/~jdieck1/chem_calc3.html

 

[Boomer]

First, why are you adding kalk to begin with. All salts when first mixed have a spiked pH, many almost 9. As you aerate the sample it brings in ambient CO2 and equilibrates to around low 8'ish. That 120 ppm Ca would end up with a Ca of around 480-500 ppm, now throw in that alk of 9, plus the IO alk of around 6+ and then the alk driven up by all that kalk you added, plus the higher pH and you are asking for trouble. Kalk drives up the pH, alk and Ca and lowers the CO2. With no CO2 in the water and CO2 is always in the air and especially if it is high room air CO2, the CO2 will pour into your tank/container like a faucet and crash the pH, once you stop adding the kalk. Aeration and windows open, like you mentioned, there is still no CO2 in the water to begin with, so aeration lowers the pH, windows open or not, as it is now driving in CO2 rather than driving it off. Have your tried aerating it for 48 hrs ? What is your fresh sea mix Alk and Ca ? If your Alk is around 6 dKH and the pH is around the 7.7 you gave and the Ca is within reason ,400 +, it is excessive CO2 causing your pH problems period.


Stop adding the kalk to the fresh mix. Make any pH adjustments in the tank. If anything I would be adding the kalk to the fresh sea mix, after I take readings on the pH alk and Ca, so I know where I'm at and not ever to the FW.

 

[Boomer]

Something you may want to try is to stir and mix the IO fully, then add some limewater if you want to raise pH (forget dripping), and stop stirring 5 minutes later. It should then retain the high pH.

Stop adding the kalk to the fresh mix

Meaning freshwater