Wizzbone

Hi guys

I have an interesting phenomenon in my tank: my Ph stays pretty stable but slowly going from 7.2-7.4 to 6.8-7.0.
My KH and GH had been stable at 3 or 4 drops but the last few months have been going down to 1-2 drops. KH should turn from blue to bright orange, but the first drop is a sort-of in between, the second drop is definitely orange!
The GH should change from a pale orange to a pale green. Well at the second drop it is definite green (compared with the orange of the KH)!

I wonder why this happen, is it bad, what can we do about it?

Some background:
5 years ago I bought this fishtank pretty cheap and fixed it up (www.signing-hands.com.au - about us somewhere) As a substrate I used a pottingmix and peat moss. The peatmoss came in a dry block and I cut it in a sandwich thick slices lay it on a bed of gravel. In between and over the potting mix. Needless t say I had lots of algae in the beginning and -once i had enough light- the plants grew very well! ..... for about 6-12 months.... Now I know that peat moss will affect the PH-KH-GH, but after 5 years?

MY routine: 1/3 water change, clean glass, thin any plants, every week and a total test: PH KH GH PO4 NH3 NO2 NO3, and everything is always fine!

The last 3 months I did do the water change etc. every 2 weeks, because the glass was still clean and the plants didn't need thinning.

So out of this information I deduct that the peatmoss might be the cullprit and that the plants don't grow because the pH/KH are to low?

Wizz

Gunnie

That would be my guess, but Dino or Butterfly are more in the know with this kind of stuff. I will bring your thread to their attention.

Dino

I would be more inclines to think the change in water changing is the cause.
I would go back to the old schedule and see if it does not correct itself.

agsansoo

Since plants use CO2 in considerable amounts, they increase the pH at the same time. Thus the pH value and the CO2 concentration are interrelated. Carbonate harness (KH), is yet another factor that effects the concentration of CO2. Hard water, with a high KH can hold more CO2 than soft water. So you face the task of maintaining both a stable pH and hardness in order to establish an optimum CO2 concentration. Hope this helps ! (this is coming from a saltwater guy. LOL )

Wizzbone

I bought some KH+ tablets, to bring up the KH.

However, I like to know WHY this happen and then adjust something in the tank to fix it, rather then adding chemicals...

Also from a science point of view: I know that CO2 affect PH (CO2 + rainwater brings acid rain), so using that info my PH going down by increased CO2 makes sense. So that means more plants? Or my lights on longer? Because of the the heat I reduced my hallide light time to 10hrs, and no fluoro-lights. last week I changed the lighting - see if that helps. 7-7 hallide, 8-6 flluoro. Seeif that works.. more light, means more co2 used by plants.....

How does the KH/GH work with CO2? I know that they are related but how?

agsansoo

OK ...
CO2 produces a weak acid, and will lower the pH of a tank. For people with moderately hard water, this works out perfectly. Those with softer water, not so perfect. Also your lighting / type of plant growth your getting effect your PH (dropping it). Has growth increased since you added the MH lights ?
If you measure your pH in the morning before the lights come on, and then again in the late afternoon, are they drastically different ? Another thought, how many watts per gallon does your tank have ?

Now as for KH reading should be between 3 and 6 (somebody correct me if I'm wrong). Baking soda will raise only the KH. If both the KH and general hardness (GH) are too low, calcium carbonate is the better choice. Another method of increasing both carbonate and general hardness is to prefilter water through crushed shell grit, crushed coral or dolomite gravel until the desired level is attained.

I don't get these hard questions in the saltwater section .... LOL