Yes it's pretty straightforward and you can use your test kits to fine-tune it

Try Charterhouse Aquatics online - I think they have the liquid versions.

Yes you're right, no need to dehlorinate if it's 100% RO as the RO filter takes out the chlorine/chloramine. Keep a small bottle of Prime on standby for emergency ammonia spikes though

Thanks Noodle

I have ordered all three items - I couldn't get the liquid ones so will have to muddle through with the powders. I will do a normal water change this weekend and then will follow your instructions to bring down the Ph - and will have a go the weekend after at using re-mineralised RO. I imagine that this change will be very positive for the tank and inhabitants At the very least I will have saved money on Rowaphos and de-chlorinator (I have a little bottle of Prime as suggested!). And it will be good not to add ANY nitrates in with the water changes in future.

I have an RO unit related question for Noodle - when do you know that you need to change the filter in the RO unit? The RO water that is coming out is measuring at about 10ppm so there is a few solid particles squeezing through. Also, do you happen to know where I could get some test calibration liquid for the TDS meter?

Thanks again - you have helped me enormously with getting things running smoothly!

Fizz

Quote:

Generally if efficiency drops such that the unit is removing <90% of solids it's time to renew the RO membrane. The pre-filters that deal with chlorine etc should be replaced about every six months on a schedule rather than by any measurement process.

TDS meter calibration fluid is available here.

HTH

Right.... - from your very helpful information I should be due to change the pre-filters

I have the RO unit you recommended which attaches to the tap - I assume the same seller would also sell the pre-filters on ebay? What do I need to buy? I would be SO lost without your help here Noods.

Sorry for being a complete noob

Just checking... to work out if the RO unit is taking less than 90% of solids would be whatever the tap water ppm measures, divided by 100 and then multiplied by 0.9? Is that right?

Quickest way is to calculate 10% of tap value and if your unit produces a TDS lower than that it's still ok. Just move the decimal point one place to the left. E.G. In my case tap TDS is 212, so the filter is working OK if it produces water with a TDS of less than 21.2 - I'd round down to 20 and replace when it hit that.

Have just tested the tap water - TDS is 300ppm so the 10ppm I'm getting in the RO is ok and I'll keep an eye on that from now on. Bit relieved actually because a replacement membrane is about £20. I have ordered some replacement pre-filters from the same seller I bought the existing unit from so should be ok.

Is there anything else I have missed? Mr F thinks I've lost some marbles with all this 'faffing about' I do over the fish tank

Cheers Noodle

Fizz

No you should be fine. Getting the calibration fluid is a good idea as the meters do drift a bit.

It's hard to explain why keeping a fish tank turns into a chemistry experiment isn't it?

I believe Violet describes it as learning to keep water, rather than keeping fish This doesn't mollify Mr F much when there's an RO unit running in the bathroom and a big red bin in the lounge full of water Nevermind eh?

Anyway, hopefully things will become more straightforward I really need to cut my expenditure on the tank for the time being - so hopefully this will all help with that.

Fizz

Hi again,

I'm just getting ready for my first re-mineralised water change and just wanted to check a couple of things I'm a bit worried about.

I have added 50litres of RO to my mixing bin and added 1 tsp of neutral regulator and 1 tsp of Discus buffer following the instructions to take the water Ph to 6.8. When I tested the water it measured at Ph6.0. I then had to add another three tsp of Regulator to bring it up to 6.8.

Is this normal? Should I be worried? I don't really understand what has happened? Any thoughts?

My second question - can anyone recommend a really easy to read PH test? The API one is driving me batty as the measures for 6.6, 6.8 and 7 are all really close in colour and hard to differentiate. Tank water appears to be 6.8 now after adding discus buffer daily.

Please help - I'm worried I'm not up to the technicalities of this re-mineralising process and am worried that I may accidently cause PH shock to the fish.

Fizz