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[APD] Re: RO/DI setup vs. CO2 setup

"The area where I live in St. Louis, MO has very hard water (high GH) also the pH tends to run around 8.0."

Hard water is not necessarily a bad thing for most plants. Test the pH several hours after it has been out of the tap. Many municipal water systems drive CO2 out of the water to make it less corrosive to the pipe system. Once out of the tap, the water will take on CO2 from the atmosphere and reach its normal pH. Ours comes out of the tap around 9 and drops to 7.6 all by itself.

"I have adjusted the pH down to neutral, with SeaChem Discus Buffer."

Discus Buffer is monosodium phosphate. Depending on how much you added, your phosphate level is now likely measured in the hundreds of ppm, when the desired level is 1-2 ppm. Keep the Discus Buffer for dosing phosphate later but don't use it for pH control. Flush the tank and start over.

"But, the water is so hard that I have been able to get an accurate reading with my test kit. The vial fills up before the endpoint is reached."

Which test kit for what parameter? You'll enjoy the tank longer if you don't fight your tapwater. So in the end, the actual value doesn't really matter.

"1) Does a test kit go "bad?""

They can, but 'user error' plays a role too. :-)

2) Would a RO/DI filter be a better purchase for the long-run than a CO2 setup?

No, buy the CO2 setup and don't worry at first about hardness. If you get into exotic plants/fish that -really- need soft water, then consider RO. Most 'soft water' plants/fish do fine in 'hard' water. Measure KH, buffer to about 3 using baking soda if needed, and then add CO2 to get to about 20 ppm using the charts:


You'll see that adding CO2 will also bring the pH down, but that's an effect not a goal.

In My Opinion, others will chime in.


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