I've used one in the past and it does work but you wouldn't want to use it to dump tap water straight into your tank unless it's a new tank setup. Like you said there's no way for you to mix the salt or use water conditioners. Even if it's a freswater tank and you predose the main tank with conditioner prior to refilling it with tap, that is not a good idea because it takes awhile for the dechlorination to actually complete. This would poison the fish and even kill some of the benefitial bacteria in the tank for the first few minutes the tap water is entering the tank. The Python's hose extensions are quite expensive too. It's really only good as a gravel vacumm or for new tank setups. In my experience and for established tanks, it's cheaper, safer, and more practica to use a submersible water pump and a good old clean bucket. That way you can get the water out of the tank and then refill it safely with premixed and conditioned water.
Back when I used to have a saltwater tank, I would just attach a length of vinyl tubing to a spare submersible pump then lower the pump into the tank about halfway, turn it on and let it pump the water out into a bucket. One bucket out equals one bucket in so you know exactly how much salt to premix and not have extra premixed water left over. To fill the tank back up you just mix the salt and water and conditioner in the bucket then pump it back in. Takes about 15 mins and much faster than gravity siphoning. The water pump is only about $6 and the vinyl tubing is about $5 which still comes out to be much less costly than the Python which dosn't do the job anyway. Personally I wouldn't use tap water for saltwater tanks. If you can use RO water.
Last edited by PaPeRo; 11/01/06 06:02 PM.
