Originally Posted by IceH2O
If you are doing a fishless cycle its possible to get away without testing ammonia and nitrites as there are no fish to hurt. But you need to test the tapwater to see if nitrates are in it, my tap has 2-3 ppm
of nitrates. That way you don't get any false readings.
If you have nitrates in your tap then you'll need to keep track of water changes. If you have lets say 6 ppm
of nitrates and filled your tank it would read 6 ppm
. Lets say you do a 50% PWC
that cuts the nitrates to 3 ppm
, but you then add 6 ppm
when filling the tank which raises it to 9 ppm
. Next time you do a pwc
it cuts to 4-5 ppm
but add back 6 ppm
and now you're at 10-11 ppm
. The good news is this is where you balance out. The bad news is you'll think your tank is cycled because you have 10 ppm
Its best to buy the ammonia and nitrite tests because you'll need them when you do add fish.
I agree you should have all 3 test kits always available. Later on down the line it is very possible to get an ammonia or nitrIte spike, and you'd never see it with just the nitrAte test. Not only that but as mentioned some tap water contains nitrAte. Mine has about 5-10ppm in it (which is great since I have a planted tank) which can be a pain when trying to monitor levels and keep water changes to a minimum and toxins in check.
The reason I quoted this post though is to correct some math. I've seen this a couple times now and it is important to make sure everyone knows how concentrations and measurements happen.
If you have 6ppm of nitrAtes in your tap water, yes when it is filled for the first time there are 6ppm of nitrAtes in the tank. ppm
stands for parts per million. This means that your tap water has 6 parts of nitrAte for every million parts of water. When I take 50% of the water out for a water change (1/2 of your 1 gallon tank) I still have 6ppm of nitrAte in the tank. The concentration has NOT
changed. If I added back in 1/2 gallon of tap water my concentration is STILL
6ppm for the tank.
Now if I take out 1/2 gallon of tank water and replace with 1/2 gallon of distilled water/RO water/etc
the tank now has 3ppm of nitrAte. You've cut your nitrAte concentration in 1/2. There are still as many nitrAte molecules in the tank as there was before adding back the 1/2 gallon in, they are just now diluted.
So using the example that IceH2O posted:
The nitrAte level in the tank before, after the first PWC
, and final are ALL THE SAME
. This is good though. It means that as long as your tap water does not change (or that you measure the tap before adding water back into the tank), your nitrAte level should always be consistent. That is, however, until your bacteria begin to consume the ammonia and nitrIte. Then every time your do a PWC
the nitrAte level in the tank can only be lower than before you did the water change
. That's why water changes are good!