water conditioning

[DrFeelgood]

I'm about to change my discus tank into a very heavioly planted tank with co2 diffuser. I have for my current set-up used water softener pillows to drop down the GH and KH and then added ;ph6.5' phosphate buffer to stabilise th ph. However this product says it shouldn't be used with lots of plants because it is a phosphate buffer.

what shoudl i do? i'm thinking about just doing the water softening and then letting the co2 ph controller keep the ph under control, but i know from past experience that without adding some sort of buffer back in the ph can swing wildly. any suggestions?

[DIY]

What is your KH/GH out of the tap? it might be you don't need to soften the water, or possibly do a mixture of softened water with water straight out of the tap. (de-chlorinated of course)

I would avoid adding ph buffers in a planted tank especially with a ph controller as you will not be able to calculate the co2 concentration. sodium bicarbonate (baking soda) is a better choice if you just want to increase the KH a small amount cheaply to reduce ph swings.

My local tap water is quite soft so I add small amounts of calcium, magnesium, potassium and sodium bicarbonate to increase the GH/KH and provide nutrients for the plants. I would never do this on my straight discus tanks though.

planted tanks are very a different beast to straight discus tanks, it usually comes down to a compromise between the needs of the discus and the plants.

for example, most straight discus tanks are run around 29-31c, which tends to melt some plants, planted tanks without discus are usually around 25-26c. I run my tank at 28-29c, any higher and my java ferns either stall or die off.

[DrFeelgood]

at the moment my tap water is pretty good - gh 7, kh 3, ph 7. It can go up to gh 10, kh 7, ph 8 depending on the time of year.

do you think this might be ok without water softening?

[DIY]

A KH of 3 is good for a planted tank with co2, I don't think GH of 7 is a problem.

It's unfortunate you get so much variation I'd suggest carefully monitoring your tap water and mix in some rainwater / RO / softened water when required to keep it around the KH 3 if possible.

Keeping your KH at a constant level means once you have set the co2 controller it will keep co2 and PH levels constant. (assuming no buffers in the water).

[DrFeelgood]

thanks for this! really useful advice, thanks a lot

[DIY]

No problem,

There's plenty of info on the KH/PH/co2 relationship around, and most co2 graphs are based on a known KH and PH to determine what the co2 is.

A handy tool which includes a co2 calculator is Chuck's Aqua_Calc that you can download here http://www.csd.net/~cgadd/aqua/art_plant_aquacalc.htm

for a KH of 3 I'd be setting your co2 controller to a PH of around 6.6, this calculates to a co2 concentration of 22. You can adjust from there based on how your plants & fish are doing.

[DrFeelgood]

cheers, m8, you're a star!