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I have slowly build up and specialised my collection into keeping and breeding corydoras. I have always tested my water when there is a problem but not regularly at all. I now have 10 tanks of various sizes and testing using test kits will cost a forune. What options are available to me. The main tests I want are nitrate , ph and hardness ( kh and Gh) I wondered if there is an all in one electronic tester?

In a word, no.
Conductivity meters are always a good idea, they are usually fairly cheap and reliable.
pH meters on the other hand are a pain, they need very regular recalibration and in my view are more trouble than they are worth (at least the models that are commonly available).
There are no Nitrate meters that I'm aware of on the "hobbyist" market.

Electronic colorimetric nitrate meters are well over £500, and all these do is digitalise the shade of the regular chemical sample.

This one does conductivity, pH and temp though.

http://www.hannainst.co.uk/acatalog/HI_ ... meter.html

I use the seperate versions of this product, and they are very good. Very accurate, and are only slighty out (pH 0.2) after months of use. Recalibration is 10 minute job, and not that much of a pain in my opinion.

FWIW... I've had three "pen style" pH meters, like the one in the link, two of which from Hanna, and none of them has survived for more than a few months. The chief problem is that if the probe ever dries out it's dead and needs replacing. Also my last probe, from Hanna, was effectively impossible to calibrate, even when it was brand new.

I may have just been unlucky or expected too much from these pen-type pH meters, but IMO they're a complete waste of money. Yes, they're better than pH sticks or paper, but just guessing is more accurate than pH sticks or paper, and IMO a decent titration kit (like the one from JBL) is not only cheaper and easier to use but also more accurate than the pen-style pH probes.

I haven't tried pen-style conductivity meters, so I don't know how they are.

Here is an idea. If you are using stable water for your water changes, get a TDS meter and check TDS daily. For a couple of weeks use the TDS meter and your test kits together. You will be able to gauge the condition of your tank by reading TDS only in a few weeks. For example, I have 12 tanks going and do not have the time or desire to test them more than monthly. I know that when TDS approaches 200 on my Discus tanks to stop dosing ferts until after the weekly water change. I also know that if any of the other tanks reach a certain TDS level, they will need more water changed out over the weekend. Aditionally, if you inject CO2, you need to get a PH meter to monitor PH daily along with your TDS to ensure your CO2 saturation is steady...DC

eupterus wrote:I have slowly build up and specialised my collection into keeping and breeding corydoras. I have always tested my water when there is a problem but not regularly at all. I now have 10 tanks of various sizes and testing using test kits will cost a forune. What options are available to me. The main tests I want are nitrate , ph and hardness ( kh and Gh) I wondered if there is an all in one electronic tester?

I just love my Pinpoint Monitor and I will never switch back to drops to chech the pH. It's only a question of taking care of it as it should be; never letting it dry, of course, calibrating it regularly, and changing the probe when needs be. . I've had mine for more than two years.