Low Calcium #'s

[scootman]

I have been doing 10% RO/DI water changes every Friday for the last several weeks. This is part of my strategy in my war against hair algae. My hair algae has begun receding. So far, so good.

I typically do my water testing in the evenings just after the lights turn off. Today was one of those rare mornings where I found myself with a little extra time on my hands. Today's water results were different than usual. For nearly a year, my results were consistently:

Ph: 8.2
Temp: 78 - 81 F
Ammonia: 0
Nitrate: 0
Nitrite: 0
Dkh: 8
Calcium: 360-380
Phosphates: 0

Today's results were different. My Dkh was only 7 and my Ph was 7.8. Is there typically and Ph swing from morning until night? Does this swing also affect Dkh or calcium results?

I have some buffers which I could use, but wanted your opinions:

I have:
* Purple Up
* Seachem Calcium
* Seachem Reef Builder
* Kent Dkh Superbuffer

Since I'm now getting into corals, the calcium count is becoming more important to me. Out of the above supplements, which would you use and how much/often? Any other ideas you may have...I'd love to hear them.

Thanks,
Scoots

[DrHank]

Your tank sounds like it's doing the same thing as mine. PH is 7,8 first thing in the morning and 8.2 by the time lights go out. My dosing pump is run by a controller which is supposed to shut off at 8.3 and seems to be running 24/7.

The only thing that I can say is that reefs seem to uptake carbon dioxide during the night and release it during the day. I think this is what is going on with both our tanks. The only thing that I can say which may be of some comfort is that tidal pools seem to do the same. It is still very frustrating when we are trying to maintain a stable PH. I'm not sure how to overcome it. If I figure it out, I'll let you know.

[JaredWaites]

If you have a refugium...try running a reverse lighting schedule. Meaning when your tank's lights are off, have your refugium lights on.

This will help with the pH fluctuation your noticing Doc and Scoot.

I don't know if it'll completely solve the problem, as some fluctuation is expected when working with small bodies of water (less than 400 gallons)...but it should help keep the pH swinging to a minimum.

Scoot,

Your Alkalinity problem is closely related to the pH problem, I don't want to get into chemistry really, but dKH is a way to measure Alkalinity.

Alkalinity is what we refer to as a buffer, which helps stabilize pH.

Essentially as Doc stated above, c02 levels can effect pH. If the c02 levels are higher, your pH will be lower. By running your refugium lights at night, your allowing your macro algae to effectly use photosynthesis to conquer the problem. By allowing this to happen your decreasing the amount of c02 that's in your tank...which will help with your pH swings.

The reason c02 lowers pH is because its a weak acid (Carbonic Acid - H2CO3).

If you don't have a refugium, I highly suggest the addition of one for this exact problem, not only that, they can help with nitrate reduction if maintained!

[DrHank]

An excellent point. I'll have to see how I can jam one in under the stand with everything else. Maybe elevated in the sump would work. I guess I'm off to Wal Mart to see what they have in plastic.

[JaredWaites]

My refugium on my last tank was elevated above the tank, I had a glass overflow in the tank, that flowed up to the refugium and back down into the tank. This is also good in the event of power failure, less things to worry about

[Acro-Phobia]

Agree with Jared on the lights. That, I think, is the main reason for running a reverse light schedule on the fug...to keep PH swings down. I also believe temperature can affect both PH and Alk. If your tank cools down at night, readings in the morning will be different from readings when the water is a little warmer.

I used to use the supplements you are using and never got comfortable with them. I switched to a two part (Kent Tech CB) and have had excellent luck with keeping parameters stable. After getting use to how the system reacts to the two part, you can refine it to get the results you want. My refinement has gotten me to 5 parts cal to 4 parts buffer of the Kent AB and that maintains Alk at 9.4 and Cal at 430. Also, switching to Reef Crystals has been a big help on maintaining Cal. Remember, a lot of it is also predicated on what biology you have in the tank and how fast they use up the Chems that you put in. Constant adjustments will be required as your tank grows and matures and you have more calcium absorbing critters.

[JaredWaites]

Temperature can play a roll in water testing. More expensive test kits, such as Lamotte and Taylor should help get rid of these issues I do believe...although I'm not 100% positive. I know at work, I have to enter the temperature of the water when I use my computer to test water...as it does play a small roll in determining the output.

[yeldarbj]

Check you Mg level too. Mg helps keep Ca levels up. I use Seachem Reef Advantage Ca, Seachem Magnesium, and Seachem Reef Builder.

[60Cubed]

Mag, if I am correct, is the vehicle that allows for the corals absorbtion of the calcium. Basically it helps the coral build it's skeleton. I don't think it helps maintain calcium levels per say, I'd check on that. But if you have any stony corals, you need mag suppliments. Reef Crystals has a higher mag level than most of it's counterparts. That is why I use it in my systems.

Alk and calcium will be affected by each other. I know that for a fact. So if you have added corals to your system that absorb calcium then your levels will deplete on a faster scale than before. Thus affecting your calcium levels and your alk and your ph. Alk keeps the water buffered so it helps maintain the ph.

[yeldarbj]

While that is true - Mg coral and coralline algae incorporate Mg into their skeletons - the presence of Mg in the water also decreases/stops additional precipitation of Ca into calcium carbonate thereby maintaining higher Ca levels.

Here is a quote from the Seachem web-site:

" Severely depleted levels of magnesium (below 800 mg/L) can cause depressed pH levels and an inability to maintain proper calcium levels. Magnesium depletion is commonly associated with the use of kalkwasser."

[JaredWaites]

Lance, lets get technical, I think both of you are right!

Let me elaborate this in a sentence or so

Magnesium is a building block for the skeleton of SPS and LPS, it serves to prevent the precipitation of Calcium Carbonate as well...which could potentially keep your Alk and Calcium levels from swinging by excessive precipitation. I know this to be true, but normally Magnesium isn't an issue especially with some salt mixes as they have higher concentrations then others of Magnesium.

If you have a high pH, your also going to have higher levels of Calcium, as Bicarbonate (Alkalinity) is going to be converted to Carbonate which is going to increase your Calcium levels. So it can have an effect...but do I think its going to play a major role in this situation? No, his tank has hardly any SPS, if any. This tells me his Magnesium levels aren't going to be consumed as fast as say a full blown tank with 200 SPS colonies in it. That size tank would obviously have a higher demand on Mag and Ca, and Alk than this one.

All in all Magnesium helps keep the Ca from precipitating and forming rock hard deposits on your glass, pipes, acrylic, powerheads, etc.

Lets get back to temperature. Higher temperatures can lead to the decrease of solubility of Calcium Carbonate and also can convert Bicarbonate to Carbonate. Which will cause the Calcium to fall from solution and precipitate due to increased levels. So as Alan said earlier, watch the temperature.

How does magnesium interfere with precipitation of CaCO3? The primary way involves magnesium poisoning the surface of growing CaCO3 crystals, slowing the precipitation. It can, in fact, be slowed to the point where it simply does not happen at rates problematic to an aquarist. In the following discussion it is important to remember that, other things being equal, alkalinity is a good indicator of the concentration of carbonate. So higher alkalinity equates to higher carbonate.

[Acro-Phobia]

Jared

My Alk was running at 10.6 and I've gradually brought it down to 9.4. My cal was 380-400 and now at 430. Reading that quote makes me wonder, should I leave my Alk alone and let it stay up at 10.6? My PH runs 8.25-8.33.

[scootman]

I appreciate everyone's input, but I'm not a chemist and this molecular "relationship" is simply over my head. I need for you guys who are chemically inclined to dumb it down a bit for those of us who are "chemically challenged".

I don't have a test kit for Mag. so I have no idea what my Mag. count is. I can purchase a test kit if needed. I'm reluctant to add a supplement or buffer without the ability to measure the results.

If I'm understanding the above posts...My low calcium #'s may be related to a low Mag. #. Increasing the Mag. may boost/retain my calcium? If Mag. tests show adequate #'s, then the water temp may be a problem? Did I understand this correctly, or did I just screw it up?

I have buffers for the alk and PH, so this is something I feel I can handle. I tested my Ph again yesterday evening and it was still 7.8. This gave me a daytime and evening PH reading. They were both the same. I've already begun the buffer for this.

Thanks again for all your help. Even if I'm a Chemical Dunce!

[Acro-Phobia]

I think it's all caused by global warming!

[scootman]

<a href=showthread.php?s=&postid=11557775#post11557775 target=_blank>Originally posted</a> by Acro-Phobia
I think it's all caused by global warming!

Yeah, it's Bush's fault my calcium is low.

[JaredWaites]

Alan,

Yes, I think leaving it at 10.6 would effectively give you what you want from the information you provided.


Scoot,

I was just rambling on. Basically I think your pH problems can be solved by adding a refugium to your tank and having a reverse light schedule. I can help you do this, its a lot to take in, especially having just gotten your feet wet

If you have low Calcium levels, it could be magnesium. If you have Calcium that is precipitating out of solution, meaning cloudy tank, and hard white spots spreading all over, then you are either dosing too much Calcium, or your Magnesium is too low, which will allow your Calcium to fall out of solution.

Temperature can effect the solubility of Calcium. If the temperature is too high, it can cause the Calcium to precipitate and form hard deposits on your tank and equipment.

I don't think thats your problem right now, as you don't have too much demand on your tank because you don't have many if any SPS or LPS.

Let me know if that doesn't make sense