...but how am I supposed to test for amonia/nitrates/nitrites while treating my tank for ich with Tonic? The water is stained dark blue, which [i presume] will skew the results. I've been doing some research and I've found that malachite green can damage the biological filtration causing a mini-cycle so I want to keep an eye on the parameters.

Bit of a catch 22, I'm afraid.

Carbon filtration will remove the stain the fastest but I have a suggestion - do 10% daily water changes and pre-treat the water you're adding to the tank with the tonic. That way you'll stay on top of any waste issues and keep your fish as happy and healthy as possible. Might as well gravel vac with the water changes as the ich cysts need to be picked up anyways.

Do you have any other (healthy) aquariums running? Use the filter media from another aquarium to seed your filter for an instant cycle once the treatment is over.

I have to say that I don't think wunder tonic would be strong enough to wipe out all the bacteria in your filter

I use malachite green and have had no adverse effects, without water changes and have had no losses not even fry.

Good to hear Jim. I've been doing a 30-40% waterchange every 3 days before re-dosing.

i have not used colouring meds for awhile.. in fact 15 years

but heres an idea

nutra zorb i think removes nit, nat and am.

but i assume doenst act like carbon and remove meds..

so if thts the case, buy one and 105 water changes??

...but how am I supposed to test for amonia/nitrates/nitrites while treating my tank for ich with Tonic? The water is stained dark blue, which [i presume] will skew the results. I've been doing some research and I've found that malachite green can damage the biological filtration causing a mini-cycle so I want to keep an eye on the parameters.

Put a control sample of untested (but stained) tank water over the colour indicator (same volume as the test sample)

if carbon removes the meds, wouldn't putting carbon in your test sample for a few minutes absorb the meds and therefore the colour?

Not sure if it is also able to absorb ammonia/nitrite/nitrate and skew the results, though if that was the case we would be using carbon as a water-change alternative...