Water Chemisty Question

[ceecrb1]

Ok so, yesterday I tested my water and all was fine, carried out a 30% water change as a finrot med has just finnished its dosage.
During the water change I added a first dose of melafix to get the recovery going...
(my water changes are 50% ro and 50% tap water where the tap water has a decalsifier attached).

exactly 24 hours later.. my water tests show a large drop in GH and a spike of KH.

What does this actually mean? what can cause this? and water changes to fix??

 

[Inchworm]

Anyone?

 

[chrisbassist]

Well...

My guess us, since ro water will be very low in both gh and kh, and you're also removing calcium from the tap water, which makes it even softer.... That would explain the drop. As for kh rising....

Not sure... Did you put carbon in the filter?

 

[ceecrb1]

I´ve been using tap/ro mix for 10 months now..... it was a sudden drop during a normal schedule.

 

[chrisbassist]

Haven't got a clue then, sorry, I thought I'd do my best to explain it since no one else has...

Do you know what the levels are out of the tap and if thyey changed?

 

[minxfishy]

Have you tested your tap water before and since, sometimes water companies change the chemistry of the water, either because of different chemicals they have added or extra chemicals because of maintenance work. Obviously these changes wouldnt make a difference to humans drinking it, but would to fish. I could be way off, I dont use ro water, but its just a thought.

 

[N0body Of The Goat]

Something that was pointed out to me when I discussed mixing RO with tap water was to take into account that water will evaporate out of the tank due to heating and this can affect (increase) kH and gH, which in turn can increase pH over time.

 

[Bignose]

Adding medications to water is going to make any test suspect at best. The test kits are assuming that the water they are testing is normal water -- that just has calcium, magnesium, maybe traces of ammonia, nitrite, and nitrate in it. Plus the microconcentrations of other stuff (chlorine, etc.). But, once you start putting in medicines and other chemicals, of course there is a chance they will react with the testing reagents.

The liquid tests all work on a titration-like reaction in that the solution goes from one color to another in the presence of certain chemicals. I wrote chemicals (plural) there because for the most part, these color-change tests will react similarly to many chemicals, not just the one you may be wanting to test for.

My guess is that the medicine reacts with the reagents of the KH test, but not the GH test. I'd just test the tap water going in to know what you put in there. If the tests from the tank with the medicine keep acting odd, I'd consider it very unreliable in the presence of that medication.