I have a 30 Litre (8 Gallon) fish tank that is heated to 26 degC (78 degF), and because it鈥檚 been so cold here, there evaporation seems to have sped up dramatically.
(I used to loose less than 250ml a week, now I鈥檓 loosing close to 500ml a week).
What effect does this have on the water chemistry?
My kH (and thus pH) fall quite steadily regardless of the kH treatment I use, could evaporation cause this?
I鈥檓 currently doing a 20-30% water change ever 10 days or so, should I be doing smaller water changes (like 10%) ever week instead?
Answers:
actually kH rises because of the evaporation - the water evaporates but calcium stays in your tank.
how do you measure kH and pH?
btw 500 ml a week is not much, my main tank loses this amount of water every 5-6 hours ;-)
comment on additional details:
do you have many plants in your tank? the plants need carbon dioxide for their growth and when they eat up all carbon dioxide in the tank and no additional carbon dioxide is added the calcium carbonate which is solved in the water crystallizes and falls out. also snails need calcium for their shells.
No keep changing the water like you are
Evaporation does have an effect oon the chemistry, but by changing the partially the water regularly the water chemistry is kept in check. Partial water changes up to 25% a week would be the ideal maitenance routine.
I always get lots of thumbs downs on this point, but I often like to tell people not to even test all these water parameters because it just makes people nervous and want to start messing around with the water. 99% of the time tap water is fine the way it is.
What I would recommend is doing 25% water changes every week, just as the previous poster suggested. Top off the tank when you need to. And then, unless you start seeing health issues in your tank, don't worry.
If you have fish that specifically prefer hard, alkaline water, then just say so and I can share tips on how to stablize it at higher levels (levels you don't really want for most types).
