low PH and Ca?

[jks1]

I have been following the threads on the board concerning ALK/PH and buffering. I have had a small problem in keeping optimum levels in my 210g SPS/Clam reef and was hoping you guys could give me some advice.

A little background. The tank has been set up since MAR this year. Its a 210 with a 75g sump. ~215 lbs Kaelini rock, shallow fine sand bed 1-1.5".
-Stoneyreef Kalk reactor (set on a float switch to replace all evap, ~4-5g/day). Reactor filled with 1/2 cup ESV kalk every few weeks, stirred 4 times a day for 1 min by aquacontroller. Effluent enters sump in a slow stream when float activates.
-CR500 Calcium reactor filled with ARM media. 20LB CO2, effluent dripped at ~ 1drip/sec, 24/7 into sump

Water tests are as follows:
Temp- 80.4 by aquacontroller
SG- 1.025 by refractometer
PH- 8.07 by aquacontroller
Alk- 10.2 dKH/ 3.66 Meq/L by Salifert kit
Ca- 310 PPM by Salifert kit
ORP- 434 by aquacontroller
Ammonia- 0 by Salifert Kit
Nitrite- 0 by Salifert kit
Nitrate- ~2.5 by Salifert kit

Also conducted tests on the effluents of the Kalk and Ca reactors:
Kalk reactor= PH-9.9, Alk-1.6 dKH/ .57 Meq/L, Ca-20PPM
Calcium reactor= PH-6.2, Alk- >16 dKH/ >5.71 Meq/L, Ca- >500

Now for the questions.. I have a fair amount of SPS, which I know are consuming Calcium. Corals are growing in the tank, but I keep wondering if the Ca were higher would they grow faster? Also I would like to see the PH at closer to 8.3? Should I supplement the reactors with some chemical additive? Should I turn up the reactors? Or am I overthinking this stuff and I should take a chill pill? On a side note I tested the PH, then vigorously airated with a pump and stone for 1.5 hours and retested. No change in PH so it is not a build up of CO2 in the water thats causing the depressed PH.

 

[cwcross]

I have been following the threads on the board concerning ALK/PH and buffering. I have had a small problem in keeping optimum levels in my 210g SPS/Clam reef and was hoping you guys could give me some advice.

A little background. The tank has been set up since MAR this year. Its a 210 with a 75g sump. ~215 lbs Kaelini rock, shallow fine sand bed 1-1.5".
-Stoneyreef Kalk reactor (set on a float switch to replace all evap, ~4-5g/day). Reactor filled with 1/2 cup ESV kalk every few weeks, stirred 4 times a day for 1 min by aquacontroller. Effluent enters sump in a slow stream when float activates.
-CR500 Calcium reactor filled with ARM media. 20LB CO2, effluent dripped at ~ 1drip/sec, 24/7 into sump

Water tests are as follows:
Temp- 80.4 by aquacontroller
SG- 1.025 by refractometer
PH- 8.07 by aquacontroller
Alk- 10.2 dKH/ 3.66 Meq/L by Salifert kit
Ca- 310 PPM by Salifert kit
ORP- 434 by aquacontroller
Ammonia- 0 by Salifert Kit
Nitrite- 0 by Salifert kit
Nitrate- ~2.5 by Salifert kit

Also conducted tests on the effluents of the Kalk and Ca reactors:
Kalk reactor= PH-9.9, Alk-1.6 dKH/ .57 Meq/L, Ca-20PPM
Calcium reactor= PH-6.2, Alk- >16 dKH/ >5.71 Meq/L, Ca- >500

Now for the questions.. I have a fair amount of SPS, which I know are consuming Calcium. Corals are growing in the tank, but I keep wondering if the Ca were higher would they grow faster? Also I would like to see the PH at closer to 8.3? Should I supplement the reactors with some chemical additive? Should I turn up the reactors? Or am I overthinking this stuff and I should take a chill pill? On a side note I tested the PH, then vigorously airated with a pump and stone for 1.5 hours and retested. No change in PH so it is not a build up of CO2 in the water thats causing the depressed PH.

Your Ca and Alk appear to be out of balance. For a Ca of 310 you Alk should be more around 2.5 meq/L or so. I would suggest getting your Ca up relative to your alk. You need to target about 420 ppm Ca or so. The problem here is that using either Kalk or your reactor (I'm not very familiar with reactors other than somewhat theoretically), will raise both alk and Ca in proportion. What you need is the calcium part of a 2 part only. Once you get your calcium and alk balanced your kalk and Ca reactors should help keep things balanced.

What sort of salt do you use? Also, have you tested the Ca, Alk and pH of your freshly mixed salt? I would be interested to know that?

It is strange that you have a high alk and a low pH. These things usually don't go hand in hand. Normally, I would say that your Ca Reactor is bleeding excess CO2 into the water and lowering pH. This is very common. You might try backing off on your CO2 injection slightly. However, since you aerated and re-tested pH, this doesn't seem to be your problem.

Also, have you calibrated your pH meter? I don't really trust pH meters. pH meters should ideally be kept in a proper buffer media all the time to keep the electrode from drying out. If not, they tend to degrade over time. Furthermore, it is good practice to calibrate them every time you use them. I would suggest to validate the pH with a colorimetric test.

a pH of 8.0 is on the low side but does can't really be called as being TOO low. It is generally lower that what people target, but not in any sort of danger zone.

I do think that getting your Ca up relative to your alk would help improve your coral growth. 310 Ca is really too low. 380 is about as low as you would want it really. 420 is considered a good target.

Have you ever used 2 part? If so did the buffer contain borate?...Thats all I can think of right now. I am really tired tonight.

Regards...Collin

 

[jks1]

Thanks Collin. To answer a few of your questions:

I use IO salt. I ran some testing and got the following:
PH- 8.0, (I use Kent buffer to raise it to 8.2-8.3)
Ca- 350
I didnt test ALK but will tonight.

I cal'd my PH pen before I took the measurements in the preceeding post. It doesnt stay cal'd long, I usually cal them every few weeks.

I have used Oceanic 2 part when I had the 29g prop tank up. I had not used it in the big 210, instead bought the reactors to control things.

As for raising the Ca. I will try the Ca part of the 2 part. Do I exceed the recommendations on the bottle to get the Ca up there, or just add it daily until the Ca is around 420?

Also I was curious about the low Ca reading when I tested the effluient of the Kalkwasser reactor. I thought that the high PH might throw the accuracy of the test kit off, explaining the low reading. Do you know if this is the case? Would you expect the reading to be this low?

Thanks for your help..

 

[cwcross]

Thanks Collin. To answer a few of your questions:

I use IO salt. I ran some testing and got the following:
PH- 8.0, (I use Kent buffer to raise it to 8.2-8.3)
Ca- 350
I didnt test ALK but will tonight.

I cal'd my PH pen before I took the measurements in the preceeding post. It doesnt stay cal'd long, I usually cal them every few weeks.

I have used Oceanic 2 part when I had the 29g prop tank up. I had not used it in the big 210, instead bought the reactors to control things.

As for raising the Ca. I will try the Ca part of the 2 part. Do I exceed the recommendations on the bottle to get the Ca up there, or just add it daily until the Ca is around 420?

Also I was curious about the low Ca reading when I tested the effluient of the Kalkwasser reactor. I thought that the high PH might throw the accuracy of the test kit off, explaining the low reading. Do you know if this is the case? Would you expect the reading to be this low?

Thanks for your help..

First understand that low pH is a typical side effect of a calcium reactor.

Your salt pH is 8.0. Thus your tank is always going to trend in that direction. You can add buffer to bring it up but as the alk gets used it will fall back down to 8.0. The salt itself contains like almost all of your buffering capacity. In salts, borate is a part of the total buffering but is not consumed. Borate, by weight is only a small fraction of the weight of the buffers in the salt, but makes up a very large portion of the buffering capacity. It may be that your tank has too much borate in it. This is why I asked if you use a two part in it? Some two parts contain borate. Over time, this will get your borate too high. This theory would explain why your alk is so high and Ca so low while your pH is low too. pH should track your alk. Are you sure your alk reading is correct? Also, how frequently and when was your last water change?

I would suggest working to get your calcium and alk in balance. You evidently have a large calcium demand. However, alk and Ca should be used in balance. Also, low Ca doesn't explain low pH. Honestly I am puzzled. Also, double check your pH. Low pH's are most commonly caused by faulty readings or equipment. If you get your alk and Ca in balance and your pH continues to stay low and you are sure that your CO2 injection isn't causing it. You might consider some heavy and frequent water changes for a while to try and establish re-balance. It is possible that you got a bad batch of salt also.

As for the two part, wait until you verify your readings. Then if you dose it, dose it over a week or so, until you establish the correct level.

Sincerely...Collin

 

[Katchupoy]

I dont have any help on your problem.... sorry.... but this link might help you....

So you would know what is the balance of calcium against alk...

http://www.caddnima.com/MYREEF/misc/calciumcalc.htm

and based on your alk above... your calcium should be around 410.

 

[jks1]

Quick update-
Ive been adding 75ml of the Ca portion of Oceans Blend 2 part daily. (manufacturers directions). Did a set of testing today at 0800 with the following results:

Temp 80.0
PH 7.91
SG 1.024
ORP 450
Alk 10.4
Ca 345
Nitrate 2.5
Magnesium 1700

Magnesium is pretty high and Im still having the balance problem between Alk and Ca. I understand low magnesium will interfere with the formation of calcium carbonate, but cant find much info on what elevated magnesium will do. Could this be throwing off the balance of things? I would think that with the Ca reactor, the Kalk reactor, and the addition of the Ca part of Oceans blend I would be able to narrow the imbalance between the Ca and Alk, and raise the Ca, but this doesnt seem to be the case. Any help would be appreciated.....

 

[jks1]

I meant to say that Ca has risen slightly (310-345), but still cannot get it into the 420 range like I would like to. Also meant to also ask if there is a safe way to lower the magnesium to natural seawater concentrations. Thanks

 

[Katchupoy]

You calcium is low... and I can recommend you the calculator because your product is not there....

But, adding calcium on your tank is not a problem... from what I know.... you can add calcium as much as you want to make the balance right...

Whats dangerous is the ALK side... you cannot add too much of this in one day...


Why not start from all over again.... I mean remove all the gadgets like calcium reactor and kalk reactor for now... then just add calcium.... at least in this case you will be able to pinpoint the source of the imbalance...

then add one gadget at a time when everything is dialed in....

 

[jks1]

Thanks Cesar, that may be what I have to do. Nothing is in dire straits now. Whats more important to me is to determine what is actually happening, then of course how to prevent it from happening again.

 

[cwcross]

It is strange that you cannot get your calcium up but you are adding it. Do you notice any precipitated lime in your tank...around heaters or powerheads are any such? If this is the case then for some reason your chemistry is such that your calcium solubility is too low, causing any excess above 350 or so to drop out. This is abnormal if it is happening. However, you need to "re-balance" your salt. This could be caused by a bad batch of salt or something like that. If that is the case then you need to start some large water changes and several of them. If you can do as much as 50%, you probably only need about 4. If you can only do less than 50% then you will need to do several changes. The other option is to consider a different salt. However, it is unlikely a problem with the salt but more likley a bad batch or somesuch.

Also, I think the suggestion of taking the equipment off line is a good one. Unless you have a really massive calcium demand, you can do without that stuff until you isolate your problem...

Best Luck...Collin