Fluval 305 VS Emperor 400

[TwoTankAmin]

Air has about 13 times the CO2 that water usually holds. Your plants will not be short CO2 useing Emperor 400s. It will constantly be replaceing the CO2 not removing it.

This is flat out not true. Water and air will have the same amounts of oxygen and co2 as long as there is surface aggitation. Without aggitation the surface tension of water inhibits the free exchange of gasses between the water and the air. However, aggitation breaks that tension which allows for the free exchange of gasses.

The reason for adding co2 to a planted tank is certain plants will consume co2 faster than it can be replaced by the normal gas exchange. So for these plants to thrive, additional co2 is needed in a tank. If you are adding co2 to your tank, an Emperor 400 will simply outgas most of it.

 

[reptileguy2727]

actually there is many times more O2 in air than in water (30,000 times as much according to marineland's biowheel information). the same would be true of CO2, and it depends on temperature as to how much gassses can be dissolved in water, so that right there will tell you it wont be the same.

 

[Grundy]

Check my signature - I have both of the mentioned filters. My Emperors are about 6 years old and are getting a bit noisier but still work OK. I added the Fluval this year and really like it - very quiet, good output so far (and I have it PACKED with media). If I was going to get filtration for a 80-90 gallon tank I would get a larger Fluval AND a HOB (either Emperor or Aquaclear - heard only good things about the AC's). Get the price of the filters online and then take it to Petsmart - they will match the price and save ypu 25-40% on average.