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johninfrance
03-30-2003, 06:54 AM
I'm getting my 80 gallon planted tank ready for my first discus. For the last week to 10 days I've been changing daily 15 gallons and putting in RO water.

The TDS evolves at each water change, but the pH remains the same at 7.2. I measure with a TDC meter and pH meter, and double-check with a solution test.

The pH of the RO water is at 5.5, and my tap water at 8.0 pH. What's the explanation for the pH being so stubborn and what would be a solution ?

Thanks,

John

Ardan
03-30-2003, 08:28 AM
Hi,
I think larger water changes may help. (with more RO)
What is the KH in the tank (carbonate hardness controls the ph stability)

hth

johninfrance
03-30-2003, 01:52 PM
It's quickly getting to the subject I'm somewhat unclear about. The TDS in the tank is now at 250 ppm, read from my handheld TDS meter (so it is really measuring µS/cm ?).

The solution test I have is GH for total hardness, and the measure is 2° in German hardness.

I've been advised to add Preis salts for Discus to RO water to add back some essential minerals - would this also act to stabilise the pH ?

John

johninfrance
03-30-2003, 02:08 PM
... and I just discovered the 'Water' topic and will read up ...

John

Carol_Roberts
03-30-2003, 03:21 PM
RO water should have neutral pH (7.0) pH will drop in your tank with the normal nitrification process. Why are you trying to drop your pH below 7.2?

johninfrance
03-30-2003, 03:39 PM
My strategy is quickly changing as I read more of the posts here, but would much appreciate any advise.

My aim now is to match my future supplier's 6.8 pH in order to best acclimate discus when they arrive. So I am adding RO water to bring the pH and TDS to a similar level. My 80 gallon planted tank will effectively become my quarantine tank.

My tap water has about 8.0 pH and 105 ppm out of facet. I don't know what it is after I age it, but will try and test.

My thinking now is once the discus arrive, add my own tap water in 10% to 15% daily changes (which will raise the pH I presume). Once the water pH and TDS equals my tap, I will then do 25% to 30% water changes 3 times a week.

If ever I look to raise, then I'll drag the RO out of the closet to lower pH again.

Does this seem coherent ?

Carol_Roberts
03-30-2003, 03:56 PM
Very coherent, but your new discus can easily go into 7.2 pH. If your pH was lower than the breeder you would have to be more careful.

Let me explain the reason for quarantine tanks . . . . lets say your discus have a horrible trip and while they left the breeder healthy, the shipping has stressed them and they become sick. Lets pretend they need treated for intestinal flagellates, a common occurance. Treatment consists of raising the temperatur to 92+ degrees and adding 400 mg metro per 10 gallons after daily 50% water changes. Right away you can see how much easier that would be in a 29 or 55 gallon bare tank. Hopefully you have a smaller tank on hand for emergencies.

johninfrance
03-30-2003, 04:07 PM
Yes, I can see it.

I have an 80 gallon, 1 x 20 gallon, 2 x 10 gallon and 1 x 4 gallon. I may be looking at changing the 20 gallon planted to BB, cause I kinda get the feeling the discus thing may get the upper hand.

The water chemistry element is intriguing to understand....

johninfrance
04-01-2003, 01:40 PM
I was just re-reading the posts - RO water is at 7.0 pH ?

dm
04-01-2003, 10:40 PM
To answer your original question, your KH is what makes your pH stubborn. Once it is lowered enough your pH will drop very fast. If you continue to try to drop your pH be careful of this. It looks like you are close now with 2° KH. Go slow and use patience.