Why is my Kh dropping?

[fastfly48]

Hello all.

Ok, heres the story...
My Kh from the tap is 80ppm, plenty hard, and my Ph from the tap is 7ppm...perfect.
However, In my tank (thats full with the water from my tap...) my Kh is only 40ppm and Ph is drastically swinging from 6 to 7ppm.

I'm injecting C02 at a very slow rate, just under a bubble a secind...because any higher and my Ph drops too much.
I haven't added any Kh buffers at all...though I did just take out a phosgaurd filter insert from my filter. Could that have affect the Kh much? I *think* that maybe the phosgaurd lowered my Kh...So I'm hoping now that It's (phosgaurd) gone that my Kh will/should rise and be the same as the Kh from my tap (80ppm)...which would make sense!

So with my low Kh, at the moment, it's making it really difficult to get much C02 in the tank with out crashing my pH...

Any ideas?

Thanks in advance.
Ry.

 

[Purrbox]

The Phosgard should only be removing Phosphates which can buffer the water but are not read as a part of the KH test. There must be something else in you water that is causing the KH to change. Since you are injecting CO2, you probably have a high light setup. What is you fertilizing schedule? I'm guessing that your plants are grabbing nutrients from you KH as a result of not getting enough of one of the ferts that they need.

 

[malkore]

First off, pH isn't measured in ppm, so don't put that after your pH readings

How often are you doing water changes, and in what volume? A 50% change once a week is the norm for planted tanks. Kh shouldn't dip rapidly. Usually it drops over the course of a couple months when water changes aren't done, the CO2 creates carbonic acid which breaks down the carbonate molecules, lowering Kh.

Otherwise, Valisneria sp. can also leech carbonate from the water colum, especially if they are lacking calcium. What's your Gh like in the tap and in the tank?

 

[fastfly48]

Thaks guys.
I'm doing about 50% a week of water changes...though more like two 25% changes than one big 50% one. That's alright right?
What's Gh? I doubt I have a test for it if I don't know what it is! Phosphate i guess?

Keep me up to speed!
Cheers.
Ry.

 

[malkore]

Gh= General Hardness (everythign else that adds to hardness of water, aside from Kh/Carbonate hardness)

Phosphate is P04.

 

[fastfly48]

thanks Malkore.
Sorry, I forget to give you my Fetilizing schedule...
I just add AZOO Chelated Ferrite Liquid every week with my water change.
On the bottle it says it's made of organic ion (not iron) complex...?

Ry.

 

[kristap]

Do you have a piece of driftwood that might be affecting the kh?

 

[malkore]

You know, I re-read your post. Just under a bubble per second? That's actually a pretty high CO2 flow. I run less than that, and my Kh is 160ppm.

I think you need to turn down the CO2 to about 1 bubble per 2 seconds, or 30 per minute.