Water changes are critical to the success of any aquarium. The Python 25 ft. No Spill Clean & Fill is best product on the market for water changes. Any new water added to your aquarium should be treated with a water conditioner, such as the Python Multi-Purpose Water Conditioner. For new tanks, or tanks with inadequate biological filtration, it’s also critical to add bacteria such as Bio-Support. And the performance of your aquarium filter will be greatly enhanced by using a product such as Bio-Clean to break down the organic waste. This package includes four Python products that work together to keep your tank sparkling clean.