PH, KH, GH Readings

Although I have liquid-based test kits for ammonia, nitrite and nitrate, I had been using test strips for PH, KH, GH and chlorine. I had a liquid-based PH test kit in the past but it seemed to give an inflated reading in comparison with the LFS liquid-based test kits (different brands) and it seemed as though the test strips (Tetra or JBL) were more accurate and in line with the LFS results. However, my consistent 6.4 PH didn't seem to "tally" with what I'd just discovered on the local water supply's website, and I was never convinced that the colour-matching of the KH was that accurate (albeit reassured by the LFS that I was reading it correctly).

Liquid-based test kits which I sent off for arrived in today's mail. My results are as follows:
* Pre-water change: KH 3; GH 4; PH 7.5 (possibly 8.0!)
* Post-water change: KH 2; GH 4; PH 7.5.

Water quality results on local website are: PH 7.3-8.2 (min-max) with avg 7.84; Ca/l 10.00; Mg/l 1.49; mg/CaCO3 31.07; Clark 2.18; French 3.11; German 1.74; Soft (<50mg/l).

Hmmm - quite a difference in PH from what I'd thought, assuming that the liquid-based test kits (Aquality - German make) are accurate (this does seem to tally in with the water supply website), and the KH and GH are low.

On the basis of the above, besides the Tufa rock, ought I to take any action to improve the KH and GH, and, if so, what? As a reminder, I have x-ray tetras (been in the tank exactly a year) and harlequin rasboras (been in the tank 5mths) but the pygmy cories didn't fare well. An Indian Almond Leaf has been in the tank for the past 5 days too.

Thanks, Sue.

Directly from the tap, the GH and KH are each 2.

I used to do smaller water changes twice a week but changed that to one large water change once a week, every Sat morn without fail, unless I'm going to be away which is very rarely, in which case I bring it forward by a couple of days and do an extra one mid-week the following week.

This is all very helpful to know, though - I'll now change this regime to 2-3 smaller water changes per week and keep monitoring the situation.

Hardness is more important than pH. As long as the fish look and behave OK, I would leave things alone.


I recently read of a study done in Germany, dissecting dead cardinal tetras that had been kept in hard water. They lived around 5 years when the life expectancy in the "correct" water is 10 years. All the cardinals they looked at had calcium deposits in their kidneys. This shows why the "correct" hardness is important.