KH Carbonate Hardness

[firstdon]

Hi all

My KH right out of the tap is at 17. I know it should be between 8 - 12. Once I run it through my DI unit and add it to my tank it remains at around 17. Is it a problem to have too high a KH? My PH once I mix a fresh batch of salt is at 8.0, so I normally add some Kent Super-buffer which raises the PH to around 8.2 which is where I want it to be. But now Im afraid to add any more buffer due to my super-high KH.
Thanks for your help

 

[reptileguy2727]

Are you using tap water for a saltwater tank? If it is a reef this is a fast track to an algae farm.

If your DI is allowing anything through it needs to be replaced. Are you running an RO as well? If not DI will be exhausted REALLY fast.

If your KH was too high you wouldn't need to add buffer.

Are you sure your KH is actually 17?
Which kit are you using?

 

[firstdon]

My DI kit is working great, no phosphates , no algae and 0 TDS Water, thank you. The phosphate test Im using is the API Kit. I will not use another kit and I will not get an RO system. Please only answer if you have an answer to my question. Is too high a KH a problem???? Wheres Greech? LOL

 

[Khemul]

Nothing wrong with a PH of 8. You shouldn't be needing buffer.

It is a bit high but way not be a bit problem. What is your calcium at? High levels alone aren't necessarily a problem, but there is a balance between alkalinity and calcium. If you have elevated alkalinity and low calcium, then you have a problem. Looks like your calcium should be in the 425 to 525 range. You could call it 450 to 500 to be on the safe side.

 

[Robert04]

Is this a Reef Aquarium or just Fish? I ran a FOWLR and I didn't worry about the KH, though if you have corals and inverts, this will be a concern.

 

[greech]

+1 to Robert 04 but measuring KH or dkh of your freshwater (which sounds like what you are concerned about) should be of little value. The calcium and alkalinity of your mixed saltwater is what you need to measure. By the time you add salt mix, the chemistry of your water will be significantly different. Am I reading your question wrong?

 

[firstdon]

You are correct Greech but even after the water has been in my aquarium for a while the KH still measures at about 17. Im using an API Test kit that was made in 2010. I heard these kits should be good for 3 years from when they were made, no? I have live rock, 2 clowns, 1 LTA, Frogspawn and Green Button Polyps

Specific Gravity 1.023
PH - 8.2
Calcium is at 300. Thats low I know and all other tests read zero ammonia etc.

 

[Khemul]

If you have an LFS nearby that does water tests you could always check with them to be on the safe side. They may charge you a little bit for an alkalinity test.

Calcium is low, you could do some dosing there to bring it back into balance with alkalinity, but you may want to get a second opinion on the KH just to be sure. I'd hate to see you throw everything out of whack because the test kit went bad, but if the test kit is right you need a little more calcium. You don't seem to have enough corals to truly warrant dosing, but your salt mix could already be on the low side for calcium (IIRC some of them do start in the 300 range).


http://www.advancedaquarist.com/2002/11/chemistry
^ If you want some information on the balance and how to correct different things in it.

 

[reptileguy2727]

If the TDS of the DI water is 0 than the KH is not coming from that. Are you saying that the tank is running 17? So this would be after the salt has been added? Have you tested the water after it has gone through the DI but before you add any salt to it or add it to the tank?

API kits are great, but not the best IME. That is why I asked. If something doesn't make sense it can be the test kits that are being used, I have seen it before many times.

I was trying to help, sorry to bother you. If you only want an answer from one person then PM them.

 

[greech]

Sorry, but just to be clear you are geting the 17 measurement from mixed SW or fresh?

Id this is SW and those other parameters are correct, something is off. You should have precipitate everywhere with a dkh of 17 and a calcium concentration of 300. Add to that your SG is only at 1.023. What kind of salt mix are you using and what are you using to test your SG?