If you have your own test kits, you should check the water any time a fish dies, and you should check nitrates about once a month to make sure your current water change regime is sufficient to keep the nitrates below 20ppm.
If you keep the test kits cool and dry they last longer. I kept mine in a plastic icecream container in the bottom of the fridge. Make sure kids and animals can't get the kits because the chemicals are pretty toxic.
If you keep the test kits cool and dry they last longer. I kept mine in a plastic icecream container in the bottom of the fridge. Make sure kids and animals can't get the kits because the chemicals are pretty toxic.