Hard Water Solution

orgetorix

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Jul 23, 2003
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Hi all. I am in the process of setting up a 300 gallon planted tank. It is still 2 weeks out from the manufacturer and I have discovered a problem. My water appears to be quite hard. I have the Red Sea Deluxe Fresh test kit. I did a variety of tests and discovered that my pH is 7.2 and KH 17dH. In the scale, this is near the high end of "hard water." I am looking for a solution. I know that RO systems are used to remove hardness, but for a tank my size, they are very expensive. If I mix the water 50/50, will the KH be around 8-9? Also, if it is mixed, do I still need a pH buffer? Finally are there other methods to reduce hardness and is it possible that I just did the test wrong? It was pretty simple and I duplicated it several times. Would another brand be recommended?
 
After living somewhere with a pH of 8.6 and gh and kh off the chart for a few years....

Unless you get a RO unit, the simplest solution is simply to match your fish and your plants to the water I'm afraid. With the RO unit it's pretty simple to adjust your water where you want it, but you'll definately need some sort of buffer to avoid big pH swings
 
How can you have a kh of 17 and a ph of 7.2? That's not just unfair, that's mean. I have a kh of 6 and ph of 8+ off the scale. Are you certain that's not 17ppm which would equal a KH of about 1? That would also explain the 7.2 pH Check your instructions one more time.

What is your GH?

I use an RO unit and use Seachem equilibrium+baking soda to bring KH to 4 GH to 4. If you mix 1/2 RO and 1/2 tap you do in general get 1/2 the kh without too much effect on ph. The tap water will act as buffer. To lower ph you could inject CO2.

I think you have a KH of 17ppm which is 1 degrees german. In that case you'll need to add baking soda or crushed coral to bring it up a few degrees.

I hope that helps. Please don't tell my you have a KH of 17 and a pH of 7.2, that would depress me.

good luck
:)
 
Originally posted by famman
Please don't tell my you have a KH of 17 and a pH of 7.2, that would depress me.

good luck
:)

Why on earth would you want a KH of 17? pH 7.2 I can understand, although that combination of KH and pH seems unlikely. Usually, with a KH anywhere above 10, pH is close to 8, and very hard to bring down with CO2.

orgetorix, I'm also thinking that you read your KH in ppm instead of degrees. Your instructions should say which. There's a way to convert between the two, but I don't know off the top of my head. You should be able to find it by doing a search. Usually, higher KH means higher pH, but additives in your water can lead to false results. Maybe someone else can help you sort out if that's the case.
 
I'll third that...

I agree with Starry and famman, the water out of my tap, once aged, is pH 7.2 and kH around 1 degree (17 ppm). Unless your water co is adding some funky chemicals to the water, I think this is the case. When I was doubtful about my conditions I just called the water company and they told me what they added and what the conditions of the water is out of the plant. Good luck!! 300 gallons is a lot, I just got a 150 and it's kickin my butt. I thought that bigger = easier...so far that's not the case for me.
 
Thanks for all your help. I decided to test again and got very different results. pH is somewhere between 7.2 and 7.4 KH is 6 and GH is around 12. Does this seem more normal. I guess I was just doing the test wrong, but it seemed so idiot proof.....
 
That sounds much more logical. It sounds like ideal water unless you are raising african lake cichlids or something out of the ordinary. With CO2, the pH will drop to 6.6 or so depending on how you have it set.
I was groaning because with a KH of 5 I still get pH off the scale. Here you were with a KH off the scale with a nice pH. Still, a KH of 6 and a pH of 7.2 does not need altering at all. I would forgo the RO.
good luck
:)
 
I was groaning because with a KH of 5 I still get pH off the scale.

Even after letting the water age? Some water companies de-gas their water (strip out CO2) to raise pH to prevent pipe corrosion. If you aerate it and let it sit for a while it should move back to a pH that corresponds to 2-3ppm on a CO chart at a KH of 5. If not, and you are having problems, I would venture to say you do not have a carbonate based buffer, but this is very old, infact I've never really seen anything like that from a muni water supply. If you add baking soda, does your KH go up in a predictable manner?
 
Yep, I get 8+ pH aged out of the tap. And yep the baking soda works predictably. When I RO the water and add baking soda and equilibrium to bring KH4 GH4 the pH is 7.4, go figure.
good luck
:)
 
if your ph isn't to wild the water should be ok for growing plants..... consistency is the thing... I bet you could grow plants in vary hard water if you got them used to it but it is a sudden change that they might pause a week or two to addapt to
 
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