Sky High KH/DKH

It's my understanding that alkalinity can be directly associated with PH. I had a nanotechnology setup for a few months and when I first started it the DKH read 12. It took about 6 weeks for it to settle at 9. The PH constantly read 8.2-8.3. I only had a few corals in it and a 6 line wrasse. The hammer and the mushrooms were good in the tank but I always had troubles with zoas opening all the way.

Just my limited experience for what it's worth.

I should also mention that my nano was a 6 gallon Fluval edge. I was doing a 1 gallon water change every week.
I think that 8.4 PH is right at the top end of where you want to be. 8.1-8.4

I hope someone else chimes in with better advice. Let us know how it goes.

How long has the tank been set up?

am i confused here or are you? KH is simply carbonate hardness while dKH is a measurment of it. Your dKH should be around 9 for hard corals and 7-8 for fish only systems. Ph is a bunk measurement. It changes throughout the day and can be affected by a lot of factors. I would not mess with any Ph buffers or anything to "fix" it unless you know what youre doin and why.

Aloha Andrew,

I agree with David and with Paul. Removing LR and LS is not the problem/solution and I would NEVER use chemicals to change pH in a reef tank. If Alkalinity is within range and gas exchange is good, pH will take care of itself. As a matter of fact it's the sand and rock that help keep Alkalinity (and pH) where it is supposed to be; 8-14 dKH. This range means that Alk can be at 14 and the tank will not suffer. A reading of 5 dKH is really low. I doubt that reading is correct, because in a new tank like this, Alk and Ca should be about the same as the salt mix.

If I had that kind of Alk reading, I would first check my Ca level to see if it is out of range; 350-500 ppm. Then I would ask someone to check Alk and Ca for me to be sure I was testing correctly/getting the right measurements.

I'll be doing tank maintenance in Sugarhouse today. Call me. I would be happy to stop in to see what's going on and check your Alk and Ca, no charge.

Aloha,
Mark
808-345-1049 call/text/visit anytime

the best thing to do is get a baseline of measurements. Do a measurement at the same time every day and track the changes. Then do it again after every water change or dosing or really any change to the system including adding corals.

Make sure you have some rock with Coraline already on it. The more the better. This will seed it into your system. It tokeeps 6 weeks before I saw coral unexpected spots on my 55s glass but I had about 30 lbs of coraline covered rock to seed it. After 3 months it relay started growing on the pumps and everything else.

DKH of 14 is pretty high but still seems OK. What I found is that if my DKH or Calcium was out of balance then I would see a lot of salt creep. I think that you want to aim for a balance of 10 DKH and 440 Calcium. Your Magnesium should settle around 1300-1350.

I wouldn't worry about testing mag in a 20 gallon system (maybe 15 gallon if you take into account your rock/sand/equipment water displacement), if you even do small water changes once a month your mag is going to be fine, if you have a lot of precipitation (white clouds/white build up on your equipment, especially equipment that gets hot), then I would think you would have low mag as thats a sign your alk and calc are binding together due to the low mag and you might want to test. DkH of 14 is too high in my opinion, especially in a low nutrient system but you didn't say your running a low nutrient system but I would target the 9-10 range as in my opinion while other ranges may be "ok" your on the fringe of safety so I shoot for the middle...the ocean is typically 7 dkh for what its worth.

Edited by Bryce - April 25 2014 at 3:29pm

phys wrote: am i confused here or are you? KH is simply carbonate hardness while dKH is a measurment of it. Your dKH should be around 9 for hard corals and 7-8 for fish only systems.

Carbonate hardness, or carbonate alkalinity is a measure of the alkalinity of water caused by the presence of carbonate (CO2−
3) and bicarbonate (HCO−
3) anions. Carbonate hardness is usually expressed either as parts per million (ppm or mg/L), or in degree KH (dKH) (from the German "Karbonathärte").
 
I'm confused also, a reading of KH (dKH) 14 is to high and KH (dKH) 5 is to low.



Edited by sabeypets - April 26 2014 at 1:17am

I am also having the same problem.  I have tested my alk twice in my tank as to try to establish a baseline of readings and am receiving the same kind of results.  When I did my testing, I received a reading of dKH of 16 and 5.62 meq/L.  Is that high or low or close to the money?  If I am reading this thread correctly then my alk is lower than it should be.  Could it be the test?  I have the Red Sea testing kit that does PH, Alk, Ammonia, Nitrate, and Nitrite.  Could the result cards be reading wrong?  All of my other readings seem to be around the "normal" area.  Ph is 8.2-8.3, Nitrates are reading around 3 and SG is 1.022.  All I have in the tank right now is some live coral and sand to establish the bacteria needed for the pump and corals.