One more quick thing - does anyone know what re-mineralising does to GH and KH - should I still be testing these or should I assume that they will be fine with the remineralising?

I just checked the ppm in the water I am heating up for the water change is measured 376ppm since I added the re-mineralising powders.

Cheers
Fizz

Test the kH, gH and pH before doing anything else Fizz. hat sounds like a lot of dissolved solids so make sure it's in the right balance. Post the reults up and I'll have a look. What amounts of the buffers did you use in how nuch water?

It's 50 litres of water. I've tested the PH again and it seems to be 6.8. I initially added 1 level teaspoon (7g) of Neutral regulator and 1 level teaspoon (7g) of Discus Buffer as per the directions on the packets. The PH reading came out at 6.0

So I added one additional teaspoon of Neutral Reg at a time until it came back up to 6.8 (3 additional 7g, 4 tspoons of Neutral reg in total).

I'll go and test GH and KH now.

Thanks,
Fizz

In the new water -

KH = 6 drops 107.4ppm

GH = 1 drop although it was really difficult to tell because the colour was so faint (17.9 - 35.8ppm)

I don't understand what is going on. When I usually add my RO/tapwater mix the ppm is around 100.

I just measured the new water and it measured 418ppm.

I think I have a digital pH meter that I haven't needed to use for ages with current fish and tap water, if I can find it I will happily lend it to you, I will go and have a look. This is all very nerve-wracking until cracked

ETA yup unearthed it, will pop it in post to you on loan for as long as you need it. It will need to be recalibrated, instructions and solution come with it

Thanks Cathie - really appreciate it.

I decided to abandon the water change today - I don't want to mess things up. I will do an RO/tapwater mix one another day when I feel up to it.

Fizz

Hi Fizz,

The buffers you you're using can increase TDS without increasing gH much because not all solids are parts of hardness. It's best for you to use the TDS meter for checking the functionality of your RO unit, but not for measuring water which has been chemically buffered. Discus Buffer can produce a relatively high TDS reading, but as there is only a small amount of "hard" solids (calcium, magnesium etc) the gH reading will be low. Which gH test are you using as I see you quoted a range rather than a single figure?

What does concern me is the amount of regulator you had to use to get the pH right, which has then produced a much higher TDS than the right dose would. Normally with RO these buffers should produce the target pH in the fixed ratio on the product label, with very little variance. Having to add so much regulator is a little odd. What pH is your RO reading before remineralising?