Water changes

How frequent should my water changes be in an established 25 gallon tank that holds about 10 gallons of water? There is no filter; only an airstone to oxygenate the water. It houses only one Cynops orientalis. I have a few live plants in there, mainly java fern, java moss, some pothos, and a bit of duckweed.

Right now I'm replacing 25% of the water twice per week. Is this too much? I'm doing more water changes because:

a) The tank has no filter;

and

b) I've been playing trial and error with how much Ladybird wants to eat in a sitting. So the last few feedings there have been some leftover frozen bloodworms that remained uneaten for an hour or so.

I'm still learning about water quality here (I read the articles on Caudata Culture), and I just want to make sure my water changes are OK. Your help is much appreciated!

Picture for reference (right now it doesn't have so much duckweed):

Your schedule is definitely not too much but you could get by with less, such as 25% weekly, especially when your plants begin to fill out the tank (and with the species that you have they will). Just be careful not to overcrowd and judging by the photo this is not the case. Also, siphon off any uneaten food soon afterwards. Nice looking enclosure.
Chip

What are the levels of ammonia, nitrite and nitrate in the tank? Do you see pH swings over the course of a week?

These will help give you the guidelines for the changes. Depending on the bioload of the tank (and the test results), you could get by with as little as 10% a week provided you replace the evaporated water with distilled or RO water or you may need to continue with the more frequent water changes.

In general, more frequent small water changes are better than large ones less frequently.

Ed

Thanks for the responses. Sorry for this late reply... I haven't been keeping track of my threads too well recently. I just bought an ammonia test kit today and it reads 0.6 on my water quality. I'm guessing that's not too bad since I hadn't changed the water since last week Wednesday. The pH stays around 7.5.

I try not to let the water evaporate too much because I know it screws up the balance a bit. So far my newt appears happy, healthy and eating heartily.

How long has the tank been set up? If it's less than a month, then the ammonia is acceptable, but perhaps you should continue the twice weekly 25% changes until it goes away. After a month or so, ammonia should always be zero as long as things stay in balance.

The tank has been set up with water and aquatic plants since June 8. I did not cycle during this time because I didn't have an ammonia test kit. It took some digging around pet stores to find one. I added the newt on June 28 (I keep a log of this stuff). So the tank has been running with a live animal for less than a month.

I think I will follow your advice and continue with the 25% water changes twice a week. I'm thinking about purchasing a small box filter for the tank.