PH, Calcium, and Aragonite

lgerold

lgerold

Active Member
Hi!

You've read about my predicament with my tank in another posting. Got another question, relating to my ph concerns.

I read in a thread started by Michiana regarding cleaning live rock, the following:

most of the rock we use is made of aragonite so it starts to dissolve at a ph of 7.8.
Click to expand...

This makes me wonder:

The reason it's been suggested that I don't use Kalkwasser to bring my PH up (from 7.6) is that my calcium level is too high. Right now it's at 560. I've been doing aggressive water changes in an attempt to bring it down, but it has even been going up slightly.

So, at a PH of 7.6, is it possible that the calcium is staying up there stubbornly because my substrate and rockwork is dissolving, bringing the calcium level up?:confused:

If so, would it actually be better to use some kalkwasser to bring the ph up above 7.8? Kind of a darned if you do, darned if you don't situation!

Lucy
 
Warnberg

Warnberg

Well-Known Member
If you calcium level is 560 what is your alk at? Usually you need a lower ph than that to get arogonite to truly disolve. To raise ph I would use baked baking soda, mix about a cup with about a gallon of RO/DI water and slowly drip this into your sump.

I would suggest you keep going with the water changes, check a batch of water before the change and see where it is at. Also you may want to have you LFS test your water as well to be sure.
 
C

cheeks69

Wannabe Guru
RS STAFF
Do you have a DSB and is it aragonite based ? Which salt mix are you using ? Which test kit are you using to measure the ph ? What are you dosing or supplementing ?

If you have an established DSB I'm sure the ph in those zones would be much lower than than the 7.6 your getting and probably dissolve the substrate but it wouldn't increase only the calcium levels but also alk and usually calcium at the 560 level there would be precipitation going on.
 
prow

prow

Well-Known Member
that is a ture statment about the ph. however, a low ph can be somewhat offset by a high alk. what is your alk? here is a good link to correct Ca and alk issues;
http://www.advancedaquarist.com/issues/nov2002/chem.htm

here is one for ph issues;
http://www.advancedaquarist.com/issues/june2002/chem.htm

and here is good one that might help with choosing a supplement;
http://www.advancedaquarist.com/issues/feb2003/chem.htm

before you do anything i would check all you parameters and try to find what the issue is. after reading the links i gave you can see the ph issue can be from different causes and trying fix a ph related problem with this or that could actually make things worse. (ex. low ph due to low dissolve O2 or high CO2 levels needs a different solution than a low ph due do a high Ca+ level) sometimes your better off doing nothing. to you in your situation we need to know all your tank parameters, including the swing (difference of high and low levels within 24 hours. a night and days reading pf your ph).
 
lgerold

lgerold

Active Member
Hi!

Thanks for the comments everyone. I'm going to do some studying on the links you included. I've answered some of your questions below:

Salt is currently Reef Crystals by Marineland. All spring and summer, I used Instant Ocean. The tank was originally set up using Coralife's salt.

Today's Parameters are:

PH: 7.81
Calc: 580
Alk: 4.90
KH: 13.8
Nitrates: 8.8 (down from somewhere over 44, good news!)
Phos: .20
Salinity: 1.025

It occurred to me finally that perhaps my RO/DI is not working efficiently. So, I checked the water I am collecting for tomorrow's 25 gallon water change. The good or bad news is that calc is 0, alk is 0, phos is 0, and nitrates are 0. It ain't the water!

Testing kits:
Calcium: Aquarium Pharm. I recently purchased a new test (same company) because I was nearing the end of the last bottle #2. I tested the water with both test kits today, and the results were exactly the same, 580.
Alk: Salifert
Nitrates: LaMotte
Phospates: LaMotte (ordered a salifert because this test does not measure below .10)
Salinity: one of those darned plastic thingys.

I ordered an electronic salinity meter which should be here in a few days. That will be handy! I also ordered salifert's iodine test and magnesium test.

I also ordered two 250 watt metal halide set ups to add to the new canapy we're finishing. The new canapy will have about 500 watts PC lighting, and the 500 watts metal halide. Also moonlights. And, we are putting in three fans to keep the air moving through the fixture to increase air flow over the water and to keep the thing cool.

Yes, I do have a DSB. I varies from a depth of 2 1/2 inches in some areas, to 5 inches in others. The substrate is mainly Arag Alive Bahama Oolite.

No precipitation of calcium. The Alk was actually down to 2.74 on the 20th, which I raised using only one does of super buffer. I was under the maybe mis-informed idea that with a depressed ph, in order for the corals to utiolize the calcium, a somewhat higher alk would be helpful.

I'll be on to my reading!

Lucy
 
lgerold

lgerold

Active Member
Hi again!

I should also have mentioned that the ph values are based on a pinpoint digital meter, calibrated using 4.01, 7.01, and 10.01. That value also is nearly the same as the level given by our local water testing facility, guaranteed to be within .01 ph.

Lucy
 
lgerold

lgerold

Active Member
Me again! I knew I had read somewhere that when the PH is low, it's best for both alk and calc to be on the higher end of normal.

So, it looks like for now the best thing is just to wait it out, and to continue with the aggressive water changes.

Lucy
 
prow

prow

Well-Known Member
sounds like your getting a handle on it. i agree the best thing to do for Ca/alk and ph now is nothing:D well how low does your ph get. what is it in the am.
nitrates yup water changes and all that other stuff. do you know what caused it to get over 44:bouncebox

i am supprised you have not got any precipitate yet.
 
lgerold

lgerold

Active Member
Hi!

The lowest ph reading nowadays is around 7.75. I've got lighting over the refugium 24/7, so the ph doesn't swing much.

I think the nitrates (and phos) because I was overfeeding. I must have been because now my big yellow tang has developed an appetite for algae. Finally.

Lucy
 
Boomer

Boomer

Reef Sanctuary's Mr. Wizard
Ok I did not go back and read all this but this sand bed, is this all new sand in a new tank ? If so I'll explain why the pH is low :)
 
lgerold

lgerold

Active Member
Hi!

I'd love to hear your explanation!

I set the tank up in February with 300 lbs of live rock, and 1 inch of crushed aragonite. In June, during a horrible cyano outbreak, I added 2 inches of Arag Alive Oolitic. At that point, most of the reef had 2 1/2 to 3 inches of mostly the Oolitic Aragonite. Last weekend, I added another 40 pounds, because areas in the back of the tank had as little as an inch.

At that time, I re-organized the tank. Being my first tank, and I an idiot, I had put the reef together in the dreaded wall form. Of course, I thought it was pretty enough, but I knew it could look better. So, while adding the Oolitic, I moved three of the base rocks into the refugium, and created a much more interesting reefscape, all to be ready to install the new canapy and lighting hopefully this weekend.

I ramble on huh!

PH in the beginning was low, about 7.7. This summer, it ran about 8.0-8.2 with a different meter. I assume though, that it was correct. Calcium always up all summer above 500. Meter died on me late in the summer, and I didn't check it again for 6 weeks, when I found the PH down to 7.7ish again.

No affect on the PH after adding the last 40 pound installment of Oolitic Aragonite. 7.74 as I type this.

Thanks Everyone! Can't wait to see Boomer's explanation :)

Lucy
 
Boomer

Boomer

Reef Sanctuary's Mr. Wizard
Well, I hate to pop your bubble but after all that info my maybe reason for the low pH is out the window. In short, fresh sand or carbonate substrate really does not buffer the water as many think, it actually lowers the pH most of the time into the mid-7's. This is because fresh carbonate surfaces have an affinity for carbonates, Ca++ and Mg++ in the early stages.

So, lets start over

I was under the maybe miss-informed idea that with a depressed ph, in order for the corals to utiolize the calcium, a somewhat higher alk would be helpful.

That is very true corals do not do good at all at these pH's you are posting.

High Ca++ and adding a buffer can pull Ca++ out of solution, it is one of the means that can be used to lower a high Ca++. When this is done there is a follow up of the Alk dropping and the pH may drop somewhat. Nothing like you are getting as your Ca++ is still high as is the ALk. So that is out the window also.

The DSB, can it dissolve the sand, ? No not really, as I nor anyone else has yet seen it happen. I'm 99.999% sure it is not but if it did you would/may get the readings you have. The sand in solution would not only raise the Ca++ and Alk but may also lower the pH. It would act like a Ca++ reactor. If or when the sand bed does dissolve in a sand bed the sand just turns into brick or large solid chucks.

You have been asked a couple of question and I have not seen a reply.

What of anything have you added to this tank.


1. Buffer, you say you did to boost the Alk just one time

2. Any Ca++ or Mg++ sup of any kind

3. Any other additives like Purple-UP

4. Any DIY or other rock that is home made or may be home made.

I find it hard to believe that your Ca++, Alk and pH are as is without adding something, unless they are all testing errors and that means all tests are in error and I do not buy that either. But pleases, for me, take a sample of water to the LFS and have them check the pH, Alk and Ca++.

A pH that low is usually a testing error or you have lots of high room air CO2. CO2 all by itself can lower the pH and it does not matter what the Alk is. I can tell you right now with that pH if it is real and that Alk, you have tons of CO2 in the water. You are near 4 ppm and normal seawater is 0.40 ppm, so that is 10x more than normal.

Some links not posted

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

Indoor CO2 Problems
http://www.advancedaquarist.com/issues/apr2002/short.htm
 
lgerold

lgerold

Active Member
Hi Boomer!

Sorry it took so long to respond - been a really busy day today.

You have been asked a couple of question and I have not seen a reply.

What of anything have you added to this tank.


1. Buffer, you say you did to boost the Alk just one time

No other buffers have been added, between the supplements when the tank was first set up in February (over done), and the one dose used about Oct. 20.

2. Any Ca++ or Mg++ sup of any kind

No calcium supplements or magnesium supplements other than what is present in Salifert's All in One which we used until June. I used Purple up for about 6 weeks, hoping that the coralline algae would begin to outcompete the hair algae, which it did do to some degree. However, I didn't like the dusty film left on everthing in the tank, which is why I stopped using it after about 6 weeks of use.

No DIY rock. Al rock work is natural, mostly live. Having said that, some of the base rock is white colored. It's real rock, but was not live when I purchased and installed it 9 mos ago. Could that be affecting the PH?

Testing at our own LFS will not give reliable results as these stores are not into saltwater. In fact, you should see their marine stuff. OMG, everything is covered in diatoms, corals die, fish die, etc. They keep the salinity at 1.016!

I can bring water to Minneapolis to be tested, but the sample would be at least 6 hours old. Will that affect the results? Especially the PH?

I did take a sample of water to a local water testing office. They do water tests for the city of Brainerd, for wells, etc. They guarantee the PH within to be accurate to .01 ph.

I use the salifert Alk test - In fact, I have two tests (different lots), and both test the same.

I use Aquarium Pharm calc test, and both my old test and my new test show the same, though from different lots.

There may be merit considering the CO2 level. It is perhaps more than a coincidence that I had ph problems when we first set up the tank in February, when the heat is on, and I am seeing ph problems again in October when the heat is on. This summer, the PH levels were 8.0 to 8.2. We are putting three fans into the canopy we are finishing not only to keep the heat down, but in an attempt to move more air over the water to try to lower the CO2 levels.

When I worked with the substrate this past weekend, none of the substrate was stuck together, or hard.

I look forward to the arrival of the magnesium test that I ordered. I'll let you know how that looks.

I'm also heading to Minneapolis tomorrow to ship puppies, and I'll bring a sample of water down with me to be tested.

I'll re-read the info on the links you sent. I do appreciate your help. Something will eventually click...

Lucy
 
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