Water change???

I have a 55 gal tank.My tap water averages about 7.4PH.I keep the tank at
close to 7.0PH.Why then does the tank drop to about 6.3 when I do a 1/3
water change? I us a Python
waterchanger.chlorine=0,nitrite=0.5,nitrate=20,har dness=50ppm,I use a a
afluvel 204 canister filter.
Thanks in advance. Skipp

[Bob]

If you keep the tank at 7.0 and it goes down to 6.3 when you do a water
change, how does it come back up to 7.0...are you adding something?

If you are not adding anything, how long before it comes up to 7.0?

Also, anything organic in the tank besides fish?

Bob

> wrote in message ...
> I have a 55 gal tank.My tap water averages about 7.4PH.I keep the tank at
> close to 7.0PH.Why then does the tank drop to about 6.3 when I do a 1/3
> water change? I us a Python

[Buzzard Face]

"Bob" > wrote in message
...
> If you keep the tank at 7.0 and it goes down to 6.3 when you do a water
> change, how does it come back up to 7.0...are you adding something?
>
> If you are not adding anything, how long before it comes up to 7.0?
>
> Also, anything organic in the tank besides fish?
>
> Bob
>
> > wrote in message ...
> > I have a 55 gal tank.My tap water averages about 7.4PH.I keep the tank
at
> > close to 7.0PH.Why then does the tank drop to about 6.3 when I do a 1/3
> > water change? I us a Python
>
>

Test the tap water before you put it in the tank. I think you might find
that its lower than 7.4 due to CO content in the water. The CO will out gas
over a few hours.

The other possibility is what Bob is suggesting. The chemicals that you are
using in the tank to maintain your normal 7.0 are a lot more plentiful than
you think. Some chemicals react with the KH in the water to create an acid
effect. If there is no KH remaining they do not work. When you add new tap
water, it has the need KH causing an acidic reaction, lowering PH. As the
acidic affect wears off, (CO2 out gassing) the PH goes back up.

Just a thought.


Buzz

I use about 1 teaspoon of bicarb of soda over a 8 hour period.I have just
fish about 15 1" to 2" long.The tap water is a little above 7 when I add
it.Once I add the bicarb it stays around 6.8 and 7.2 Until the next water
change.Thanks Again Skipp
> wrote in message ...
> I have a 55 gal tank.My tap water averages about 7.4PH.I keep the tank at
> close to 7.0PH.Why then does the tank drop to about 6.3 when I do a 1/3
> water change? I us a Python
> waterchanger.chlorine=0,nitrite=0.5,nitrate=20,har dness=50ppm,I use a a
> afluvel 204 canister filter.
> Thanks in advance. Skipp
>
>