[duster]

My SeaChem ph/alk test kit measures alk in meq/L. It says that seawater measures 2-3 meq/L, but an aquarium should measure 4-6 meq/L. It also says you can multiply your meq/L test result by 2.8 to get a KH reading. Are KH and dKH the same measurement? In looking at livestock from online retailers, many recommed a dKH of 8-12, but an meq/L reading of 5 or 6, which is good according to my test kit, would equal a KH of 14-17, which according to things I've read is too high. But if KH is different from dKH, then maybe I'm O.K. with readings of 5-6 meq/L.???
Is there such a thing as having alk too high? I would think the more buffering capacity the better, but maybe not.

[Reefland]

Hi duster,

This might be best off answered by the Randy Holmes-Farley:
http://www.advancedaquarist.com/issues/may2002/chem.htm
http://www.advancedaquarist.com/issu.../chemistry.htm


In a nutshell, yes ALK can become too high and make it impossible to balance calcium levels and pH. Also KH and dKH are the same thing, a measure of carbonate hardness. Mutliplying your ALK result in meq/L by 2.8 will give you dKH. I would recommend that you try to keep your ALK at 3-4 meq/L, the higher end of that will make it a bit harder to raise calcium levels to 420-450ppm.

[Ninong]

KH is an abbreviation for the German words karbonate harte (carbonate hardness). The unit of measurement of KH is the German dKH (degrees of carbonate hardness). The metric unit of measurement is mEq/L (milliequivalents per liter).

Divide dKH by 2.8 to get mEq/L or multiply mEq/L by 2.8 to get dKH.

What is recommended depends on a number of factors. What is best for one person's particular tank may not be best for another person's tank. That is why most authors simply recommend "safe" ranges instead of bothering to explain in detail why a higher or lower level may be either better of worse depending on other parameters in your tank. Delbeek & Sprung recommend dKH of 7-10. Some other authors recommend 10-12 dKH. One very well known expert hobbyist maintains his personal reef tank at 12-14 dKH.

A reasonable one-size-fits-all range would be 7-12 dKH. If you are at the low end of that range and your nightly pH is dropping below 8.0, then you should raise your dKH. If you are at the high end of that range (or higher) and you are having trouble keeping your calcium above 400 ppm, then you should lower your dKH.

The guy who keeps his tank at 12-14 dKH also keeps his calcium at 450-500 ppm and his pH at 8.0-8.2, his specific gravity is usually around 1.023-1.024, his temperature at 78-80F in winter and 80-82F in summer. Those numbers work very well in his particular situation because of his equipment and his procedures.

Everything in this hobby is intertwined with everything else. Things that may not seem related at first glance, actually are related. It may not be a good idea to copy one or two parameters from someone else unless you are able to copy ALL of his parameters, including lighting and water movement.

If you want to play it safe, just go for 3.0-4.3 mEq/L (8.4-12.0 dKH), 8.0-8.4 pH, 425-450 ppm Ca.

[duster]

Thanks for the info.
When I mix up saltwater with filtered water and Instant Ocean salt mix to an SG of 1.024, I get an alk of 4 meq/L and a pH of barely 8.1 (under no lighting in a mix container). I have two supplements to experiment with: Kent OSMO Prep Marine and SeaChem pH Buffer 8.3. When the recommended dose of OSMO Prep is added to my mixwater (1 teaspoon/5 gal.), it raised my alk to 6 meq/L, which I'm guessing is too high. I'm in the process of testing the SeaChem. I'm not sure these numbers matter much now anyways, because as soon as the tank is stocked and being fed, the numbers might change. Time will tell.

[Reefland]

duster, if you are getting 4 for alk and 8.1 for ph in water change water after a good 12-24 hours of mixing, I would be ok with that and personally wouldn't bother adding anything.

[duster]

Originally Posted by Reefland

duster, if you are getting 4 for alk and 8.1 for ph in water change water after a good 12-24 hours of mixing, I would be ok with that and personally wouldn't bother adding anything.

Thanks Reefland, that's actually what I was hoping to hear. I don't want to add any more chemicals or supplements than I have to. If I start having water parameter troubles, I'd rather fix the source than cover it with chemicals.

[balistik1]

So if the Alk is too high, how do you lower it?

[Ninong]

Originally Posted by balistik1

So if the Alk is too high, how do you lower it?

If alkalinity is too high, it usually means that you have been overdosing alkalinity relative to calcium. Therefore you solve it by discontinuing the addition of any alkalinity supplementation for a period of time while you continue to dose calcium.

You should dose calcium chloride to maintain your calcium levels during this adjustment period. You cannot use limewater because it is a balanced additive and you want to allow your alkalinity levels to fall.

Of course you could always do a few large water changes if you are looking for quicker results or if your numbers are really out of whack. What are your current readings on calcium, alkalinity and pH?

[balistik1]

I am at work so I don't have that information available. I can tell you that I do not dose alk and my levels are still high.

[Ninong]

Originally Posted by balistik1

I am at work so I don't have that information available. I can tell you that I do not dose alk and my levels are still high.

Do you add anything at all to your tank?

[balistik1]

Well when this all started no my alk was just high on it's own. Then I startedt o add Cal to try and help give a balance and I noticed that my PH was a little low so I am also trying to raise that.

[Ninong]

Originally Posted by balistik1

Well when this all started no my alk was just high on it's own. Then I startedt o add Cal to try and help give a balance and I noticed that my PH was a little low so I am also trying to raise that.

If you are adding buffer in an attempt to raise your pH, then this is the cause of your high alkalinity.

Perhaps it would be a good idea to do a 30% water change (if possible) and discontinue adding anything for a week or ten days while you measure your parameters to see what you have?

[balistik1]

So by raising my PH I raise my alk?
Is there a way to raise PH without doing that?

[Ninong]

Originally Posted by balistik1

So by raising my PH I raise my alk?
Is there a way to raise PH without doing that?

I don't know for sure if that is what you did because I don't know exactly what you did in an attempt to raise your pH. Did you add anything to your tank in hopes that this would raise your pH?

[Ninong]

Suggested reading:

Reef aquarium water parameters: http://www.reefkeeping.com/issues/2004-05/rhf/index.htm

Solutions to pH problems: http://www.advancedaquarist.com/issu...e2002/chem.htm

Calcium and alkalinity balance issues: http://reefkeeping.com/issues/2002-...ature/index.htm

The relationship between alkalinity and pH: http://www.advancedaquarist.com/issues/may2002/chem.htm

Solving calcium and alkalinity problems: http://www.advancedaquarist.com/issues/nov2002/chem.htm

Calcium: http://www.advancedaquarist.com/issues/mar2002/chem.htm

Alkalinity: http://www.advancedaquarist.com/iss...2/chemistry.htm

How to select a calcium and alkalinity supplementation scheme: http://www.advancedaquarist.com/issues/feb2003/chem.htm