High Alkalinity, 450 Calcium very low PH (7.3)....Help!!!!

[khines5330]

29 Gal. reef tank
45lbs Live rock
Protien skimmer
UV
Cannister filter

Water parameters:
KH = 15.7 dKH (Using a Nutrafin KH and Seachem KH tester)
Ca = 452 (Pinpoint Ca Meter)
PH = 7.32 @ night 7.15 (Pinpoint PH meter and Nutrafin PH Tester)

As far as I know and have read....... typically when the KH goes up so does the PH but for some reason not in my case. I use Oceanic Seasalt mix with a PH of 8.2, I have done 6x50% water changes bringing the KH down to 15.7 and the PH stays at 7.3. I have only used Kent Turbo calcium (Ca Chloride) so as not to add any alkalinity to try to percipitate the alkalinity to no avail.
Im lost, please help

PS; I do not have a Calcium reactor so C02 is not enter the system in excess to create a lowering of PH.

 

[m-fine]

I think the only way those numbers are possible is if you have excess disolved C02 or you are adding some other acid. You likely have one or both of the following problems....

1) Not enough aeration to get C02 out of the tank water.

2) A high level of CO2 in your home which is not uncommon in newer non-drafty homes

You can try adding an airstone or two to the sump and also try blowing fresh (outside) air into your skimmer and airstone and see if that does not make a significant difference after 12-24 hours.

You may also want to try a different PH tester or test kit, or bring a water sample to a LFS just to verify that your are not seeing a testing problem.

m-fine

 

[Anonymous]

Test a batch of mixed Oceanic salt to eliminate the chance that you have received a bad batch of salt that just has a super-high carbonate content. Is there a lot or precipitate at the bottom of your salt bucket after mixing?

Remove a gallon of water from your tank, aerate it with a stone, and then test PH after an hour. If PH is normaly then I agree with (1) posted by m-fine.

If the sample is still low in PH then take it outside and do the same aeration.

If the PH is still low then I think that somehow both of your PH testers got out of whack at the same time - 1 in 1,000,000.

 

[Mihai]

I believe that the PH test is out of whack. There is no way to be that low. Or the Alk test is bad. One of them got to be.

M.

 

[khines5330]

I have checked, re-checked and double checked all testers and probes. All reading are very similiar. The test equipment are not it.

 

[Mihai]

OK, something is out of whack: have a look at this article, especially at Figure 2. For the readings to be right, you either don't have sea water, or you have pure CO2 in the room (or close to it):

http://www.advancedaquarist.com/issues/may2002/chem.htm

I'm telling you that something is not right.
Do the following two experiments:

measure with all your tests (only pH and Alk) some freshly prepared and aerated sea water (aerate it with a air pump inside your house - close to your tank). See what you get. BTW, what brand of salt do you use?

also take some water from your tank, get it outside and aerate with outside air (also with an air pump) and repeat the measurements (only pH and Alk). If it's CO2 it will show.

Another source for low pH can be the vinegar if you use some in your kalkwasser - do you?

Mihai

 

[Mihai]

Besides, it seems that your high Ca and Alk cannot really coexist at the same time at your values. See:

http://www.advancedaquarist.com/issues/nov2002/chem.htm

M.

 

[Anonymous]

Besides, it seems that your high Ca and Alk cannot really coexist at the same time at your values.

.... unless an excessive amount of Borate was inadvertantly added to the salt mix.

I still think the replacement water needs to be tested to eliminate it as a cause.

 

[khines5330]

Fresh salt mix w/ RO/DI water = 8.18 (PH)

Aquarium water aereated for 2 hrs outside = 7.51

Aquarium water before test = 7.46

I use Oceanic natural sea salt mix

 

[zombiereef]

i have heard that oceanic has had some quality control issues lately and there are a bunch of bad batches of salt out there. you may have gotten one. is it a new batch of salt or a batch you have been using for a while?

 

[khines5330]

I tested the salt for PH and its basically correct, so I doubt the salt would have anything to do with such a low PH and high alkalinity.

 

[Mihai]

Sorry, I'm out of ideas then. I'm pretty far from a chemist, so I don't know. If it would be to guess, I'd guess that you have *something* in the tank that's not supposed to be there that is lowering your pH although the Alk is high... perhaps you may want to PM Randy Homes about this problem, maybe he can know what is it. It has to be some kind of an acid to lower the pH.

Anyway, I think more important than figuring out what caused it is correcting it (maybe not). Given that the freshly prepared salt looks good and that the CO2 doesn't seem to play a role in here, I suggest you get to an aggressive water changing schedule (not too aggresive as swinging the pH fast is a sure way to kill inverts). That will take care of your problem whatever the problem is.

M.

 

[Anonymous]

Can you test the ALK & Ca on your new water? PH doesn't say much.

 

[alice_curiouser]

I came across this thread while searching for answers on why my own ALK might be high (15.68 dKH) and pH low-normal (8.0 at noon). I have seen a couple things about high levels of undissolved Co2 and poor aeration, and I wondered if covering the top with glass tops could contribute to this problem. I recently bought a hanging light fixture, but until then, I used glass tops to keep my lights out of the water. I have since (last month) replaced them with eggcrate, but my ALK is still high. Could the glass tops have caused the high alkalinity, and if so, will the problem correct itself over time? I plan to buy a small pump and airstone to try, as well. Thanks for any insight!

 

[khines5330]

I never had a top on my aquarium so it wasnt my problem. No top on the aquarium is better as it allows better gas exchange.

As far as my aquarium goes, the PH is still high but I have been able to lower the alkalinity to 9.6dKh. My PH hover around 7.6 in the day and 7.4 at night. Everything is growing very well, so I decided to let everything take its natural course.

 

[Anonymous]

The only way to get high ALK is to add buffer like Carbonate or Borate. You could test your salt mix to see if it's coming from there. What other additives are you dosing to your tank?

They there's always the chance that the test kit is reading high. Testing your salt mix can eliminate that as a possibility.

 

[alice_curiouser]

Khines5330 - I know the glass tops aren't good, but for a long time no-one told me, and even when I did find out, I was using a PC light strip that couldn't rest on the top without it. As soon as I got my new MH/VHO fixture, I ditched those suckers.

Guy - I use no chemical buffers. The only additive I use is Aragamilk, and then only occasionally (meaning, when I can remember it). I've not yet tried testing my new water, but I will do that tomorrow when I re-test the tank.

The reason I wondered about the glass tops is, I have a friend with the same problem, and the only thing our tanks have in common are the glass tops.