Co2, Kh & Ph

[Squirrelbuddies]

I think I'm having brain fade as I can't quite seem to get a grip on this --- My KH is normally 4 degrees and I have pressurized CO2. pH reading is 6.6. Based on the chart, this equates to 30ppm of CO2.

Within the past week, the KH is now measuring less than 4 (between 3 and 4). So, if I plug that into the chart it would indicate my CO2 is now 26ppm. (pH is still reading at 6.6).

This doesn't make sense to me as there is no change in the amount of CO2 being injected - so the amount of CO2 should be the same, right?

Also, why has the KH dropped? I have a good load of vallis in the tank -- could that be the reason? (It seems I read recently that the vallis will do that... Are they not receiving enough NPK?)

Anyway, hope someone can set me straight.

 

[Themuleous]

Are you sure the pH kit isn't reading more like 6.5? That would give you nearer the 30ppm. Also are you testing at the same time during the day for both? My pH goes from around 6.6 in the morning to 6.8/.9 in the evening as the plants use the CO2 during the day.

As far as I know valls use bicarbonate as a subsitute for CO2, but as you've got loads of CO2 in the tank I doubt if the need to do that. So reckon its either the tesk kit not being sensitive enough or the time you're testing.

Sam

 

[Squirrelbuddies]

Sam, good point about the test kit. The scale goes from 6.4 to 6.6 and the difference in color isn't too significant. So I bet it really is coming in at 6.5. That makes me feel a lot better! I was beginning to think I was losing my mind but then I realized I lost it a long time ago!

The pH used to fluctuate between early AM and late PM - but now that I have the pressurized system (which shuts off with the lights at night), it reads pretty much the same day or night.

 

[Themuleous]

glad to help