I don't think so. To be safe, make sure heater doesn't directly touch the plastic; some heaters even have a guard.
I've always been under the impression that large swings in temperature can stress the fish out? Especially large drops? Correct me if I'm wrong here, but 10°c seems like a large drop? I realise that the tank won't drop 10°c just because I put 100ltrs of 15°c water in it, but wouldn't the change stress my fish out regardless? I'd have no problems doing something like that with my goldfish, as they're practically invincible, and that's most likely how I'm going to have to fill up the pond when I get them in it.You don't need to match the water temp exact, I do water changes with ~15 degree C water, and the heaters in the tank will raise the water temp back up. Also I add prime as the hose is in the tank.
Also just using a long hose pipe, going out doors (on to the garden) means I do water changes on all my tanks with not more effort then just pulling hoses around. It makes life a lot easier.
Sweet. Especially the last bit. The four foot tank is a S.A community tank. Although I still don't think I'd trust doing so with the 2½ foot. Most of the fish in there dont appreciate anything colder than 23°c, and I have an older (over 3 years) betta in there that I don't think would like it much.. But I might try it with the goldfishs tank, and the four foot next time..It depends on how much you change, I only change about a third, so after a change the tank is 2/3 at 25, 1/3 at 15 so it is only dropping to about 21/22, still in a fine temperature for most fish, and only a small drop of about 3 and 1/3.
A lot of fish don't mid a temperature drop, and especially those from south america a temperature drop triggers spawning.
I've never seen safe, I'll ask the guy at the shop if they can get it in, if they can I'll give it a try.Hello; I bought a bottle of SAFE which is the same as PRIME only in a powder form. Made by the same company, Seachem. A 1kilo (2.2 pound) bottle is supposed to treat 200,000 gallons US volume and cost me $32.00. A 100 ml bottle of the PRIME cost me $4.99 and treats 4,000L (1,000 gallons). Quite a saving.