Basic chemistry questions

[_Nemo_]

What water chemistry parameters would you ideally want in a planted tank?
pH, kH and gH?

My kH is very low, about 3 dKh causing pH swings. I want to minimise raising the pH. What is the minimum kH needed to maintain a reasonably stable pH?

Thanks

 

[tkos]

I have a very low kh and gh but plants grow very well in my tanks. I just have to make sure to do decent (20-25%) water changes every week to keep the pH at the same level as the tap water which is around 7.4. If I let it sit too long then the plants use up the buffer (and the bacteria as well) and the ph starts to slowly drop. I found this out when my mom had been doign small water changes every week and the ph fell to under 6.

 

[malkore]

Usually a kh of 3 degrees is sufficient for pH buffering, even allowing you to inject CO2 with minimal risk. it's when your Kh is 0-1 degrees that you have real problems.

what pH swings are you seeing exactly?

 

[_Nemo_]

Thanks for all the replies.
I do not currently have a planted tank per se
Current setup:
- 25 gallons
- 5 plants
- 18 watts light (don't laugh please)
- no CO2
- 1 adult , 2 juvenile platies
- 5 neon tetras
- 2 pieces of mopani wood
- 300gph rated power filter
- 100W heater

gH = 3
kH = 3
Temp = 79-80 oF
pH = 7.8 - 7.2 (over a week say)

1-2 x 25% Water changes weekly
Tap water
gH = 3
kH = 4
pH = 8.2

Symptoms - dead neon tetras

 

[TankGirl]

I am going to agree with Malkore that if you have at least KH 3 then you are in good shape, but if you have a filter that permits different media then you can add crushed coral to it and increase your KH without any trouble. It will help to stabilize things, especially if you do put together the lighting setup you are considering, With 75 watts you will need to use CO2 (Hagen system is relatively cheap and easy to do for a smallish tank like yours) and you will find your pH dropping, but without it you will have algae problems.

 

[_Nemo_]

Thank you all!