Can plant growth lower KH?

[Waterloo Kid]

I'm having huge and dangerous pH swings due to low KH. I was wondering if sudden plant growth could remove the compounds that are responsible for maintaining the KH value of the water.

WK

 

[George Farmer]

I have heard of this. Some plants i.e. Vallisneria sp. use carbonates in the water so one could assume if there is a lot of growth then the KH may drop. Not sure about other species - if you have CO2 injection then I would imagine they get the carbon from that rather than extracting it from the carbonates in the water.

Your KH is on the lower limit of what many regard as safe i.e. 2 degrees. This may be the cause more than plant growth.

 

[iggy01]

Yes! plants can use up some of the KH in your tank, but as gf225 states, you have a Co2 supply so the plants will use that as the carbon source. It's usually people with no Co2 injection that may notice a fall in KH.