Not really sure which category this question belongs in, so I posted it here and in equipment. I just purchased a penn plax cascade 700 for an established 55 gallon planted tank. I currently have a HOB filter. My question is, what's the best way to get the filter setup with the proper bacteria? Should I dose the tank with something? will the dosing cause an out break of algae because the tank is already established?
My response is based on the information in your opening post ie; "an established 55 gallon planted tank".
Leave the old filter in place running and add the new one allowing it to naturally seed for several weeks then simply remove the old filter. Betting you wouldn't be comfortable simply removing the old one the same day as you do the replacement,,, but you could. (and which I've done several times)
Unlike a fish only tank that is solely dependent on the filter media planted tanks have not only the living plants but an increased overall surface area containing the same bacteria that's in the filter media. While running a filter on a planted tank is what most of us do simply a sponge equipped power head can support a fully stocked, established planted tank.
Here are four 55's "filtered" only by sponged power heads
The Fraternity of Dirt
If at first you don't succeed,,, keep kicking it RubberSideDownOnTheLanding, 2-75g planted, 5-55g planted, 5-20g planted, 110g w/30g sump, 8-10g, Refugium, doghouse/newbie 2012 update adding table top pleco pans & a 90g (Nutz)