Messed up again I think?

[blk822822]

Well my last post was because my KH was low, I used baking soda mix to bring it up to 11. Everything looks good in my tank today but I have been having a problem with ca being to high, about 650. I have been doing water changes with Ro water and it has come down to about 550. The test kit I have is a API kit. I just tested my ph and it is between 8.0 and 8.2, KH is 11 ,and CA is still around 500 to 550. What should I do to bring up my PH and lower my CA? Are these test kits junk? I have a 75gal tank with 80 lbs live rock ,20 lbs live rock in the sump with macros, 70 to 80 lbs of live sand , and I have been using RO water and doing Bi weekly water changes of 7 gals to bring down the CA. Should I be worried about the PH and CA???? Please I need advice, I have been doing the reef for awhile but never really had SPS corals so didn't mess with the CA and Mag and stuff. I don't have a bunch of money to buy good test kits yet so I just want to keep from killing corals or fish.

 

[thatguy559]

why would you need to lower your calcium? i use to run mine at 650 all the time....great coral growth. do you have a ca reactor? you can use a ph buffer to raise it but be careful too much to fast will harm your tank. i had my ph at 8.2 and my ca at 650 for 3 years with no issues and great coral growth. and clam growth.

 

[blk822822]

Ok , I was just worried because it says your ca should be at 450. Ph dosn't swing ,just used to be at 8.4 all the time. Like I said everythin looks great just when a testkit is off its chart I wonder.

 

[thatguy559]

well challenge your test kit bring you water to a local fish store or a couple lfs and get it tested there to see if your kit is bad ph should swing during the day it should be higher thank during the night my ph was 8.2 during the day and 7.9 at night

 

[blk822822]

I think I will do that tomarrow. Good advice.

 

[thatguy559]

not a problem

 

[returnofsid]

Your pH is just fine. While your Ca is a bit high, a lot of people run their tanks with high Ca. You can let your Ca naturally drop, over time. As long as your Ca and Alk are balanced, and your Ca is above 380, you're just fine. I'd recommend testing Magnesium as well. It's just as important as Ca and Alk. Mg should be 3X your Ca.

 

[lvsuckerfish]

how many sps do you have in your tank that you are dosing with a few sps you can get away with just water changes dosing comes to play with alot of sps and lps that need to build skeletons. at tops I would drip kalk real slow 1 drop per 10 seconds but not until you have everything inline first.

 

[jrgilles]

I'd say don't worry about the high calcium, but wait for it to go down with water changes.

Once it is down, start a kalk drip, which will maintain calcium and raise the pH.

From what I understand, the bad effect of having calcium too high is some of the minerals might drop, because the water can only hold so much. Might precipitate a bit of magnesium, etc., and probably most notably, you could get calcium deposits on the glass, in the plumbing, etc.

Not really a big deal if you let it drop back down to normal.

You'd think someone in kent would have a Ca test you could borrow for diagnosing your test kit.

If you are heading to seattle today, feel free to stop by with some tank water and we can test you ca, kh, etc to varify your kits. I have all sorts of test kits, that are all just a few months old.

rob

 

[jrgilles]

I notices a lot of the pH kits read artificially high (diagnosed this when I got my pH probe.) If you end up coming by with a water sample, we can test the pH with my probe also to see what you are really at. I've verified that my probe reads correctly by testing my water on 3 different pH probes in the lab I work at (that I know are accurate.)

 

[Boomer]

I notices a lot of the pH kits read artificially high (diagnosed this when I got my pH probe.)

Actually, it is the other way around in seawater i.e., pH probes read artificially low when compared to some pH test kits which are adjusted to seawater, where pH probes are not. However, we and almost all others in the science community, almost always go with the probe reading. If we were to look at the real pH of seawater, @ 35 ppt NSW, meter reading pH 8.3, the real pH is 8.15. This is due to the "salt effect error" and yes some pH test kit are also subjected to this and read low like a pH probe or even lower. Those pH kits that give "real" seawater pH are such kits as the SeaTest/FasTest/Instant Ocean and Kordon Saltwater pH kit. There are technically 2 pH scales, pH-NBS, for FW and pH-SWS for seawater. We use the pH-NBS and in print it will always be pH-NBS, unless it is cited as being pH-SWS.

 

[jrgilles]

Ah, thanks for the clarification. So, even though I varified my pH probe's reading using several laboratory probes that I know read correct, they are all off due to the salt effect? Would have3 been nice if the guys at apex could have told me this...

So, since 8.3 on multiple test kits read about 8.1 on my probe, should I be trying to hold my tank at a probe reading of 8.1 instead of 8.3 (since apparently 8.3 is really not true, and more like 8.5 or so)?

Could you add salt to the calibration fluid to make up for this salt effect? I'd think that wouldn't work, but just curious.

thanks boomer!
rob

 

[Boomer]

rob

Don't let this bother you. Nobody but seawater researcher do and only for special purpose. If you got a book on seawater chem they will give the pH of NSW the same as your probe does. It is only used when the real pH is need for certain types of chemical calculation where you need to know the exact pH. If there were not a couple of seawater test kits out there that were not pHSWS and where pHNBS you wold have not gotten this post. If I tell you the pH of NSW is 8.1 -8.3, that is the same as your meter Run your tank on the meter reading. I wish these test kits never came out. The marketing hype was "adjusted to NSW"

For meters, you don not really have to make -up a solution it is just math.

phSWS = pHNBS(meter) + log fH

fH = a correction for salt error.

fH = 0.739 + 0.0307 S + 0.0000794 S^2 + 0.00006443 T - 0.000117 ST

Where T is temp in kelvin and S is Salinity in ppt.

So, at a temp of 25 C @ 35 ppt


fH = 0.709

phSWS = 8.3 + log 0.709 = 8.15

No how just forget this Meter as is OK

 

[jrgilles]

Excellent answer, thanks for posting. That makes it all very clear. I agree that they really should have just stuck to 1 reading.

As a biologist by trade, this error in the reading was bugging me. Much happier now that you posted an equation for it. Now, I'll forget about it (well, after doing a few sample calculations maybe..)

rob