Since you can not go wrong ... 1

I use AquaSafe for several years and with absolute conviction. Earlier in 3, now in 2 aquariums improved AquaSafe water quality to such an extent that even my available standing very hard, sometimes brownish discolored by line cleaning or old lines and partly chlorinated tap water appears absolutely bright and after filling the aquarium a slightly bluish, clear appearance leaves.
The dosage is easy with the help of the cap and the dosage instructions on the bottle back, I personally Dosière by feel. It makes the fish and do not mind if a few more times to land milliliter in the water bucket. Mir is still entschwommen after a partial water change is no fish in the happy hunting grounds, to say it does not lend itself for slight overdose damage to the animals.
The bottle size, I prefer from preislichem reason and also because of the longer of use, maintenance 500 ml in it.
Well, and algae growth is also limited, the water purifier neutralized proven moderation kinds existing pollutants in the aquarium water. Of course the growth of algae can be thus not completely prevent, also solles not, some fish are indeed now time to algae, and finally growth of algae depends inter alia on the location (sunlight), number of fish (amount) and the amount of feed. For problematic algae growth there in the house as well as Tetra functioning remedies ...