i have a 17g, 15lbs LR, 20lbs "live" sand, mp10.

just got done with the cycle. currently levels: amm 0, nitrite 0, phos 0, nitrate was 20, but i just did a 50% WC so perhaps nitrate 10.

the tank was cycled for about 15 days. how should i maintain the sponge on the ac50, which has been on the tank since day 1 of the cycle. i have 3 new sponges. theres carbon and ceramic pieces in the ac50 too.

i will replace the ac50 out with a rena xp2 in about a month.

so how should i maintain the sponge on the ac50? it'll go on a 10g QT in a month.

the sponge is there to trap particles and will also grow good bateria in it. you can reuse them but they need to be cleaned and rinsed in old tank water (when doing a water change). or you can rinse it with tap water but it will wipe out the bacteria. the ceramic pieces are soley for nitrifying bacteria to grow on and many people will say to not use them. they do work but will keep nitrates at a higher level, which is ok for some tanks,depending on what you want to keep. sensitive corals like sps need very low nitrates. if your quarentining new fish your qt tank should be established (cycled) just like your display tank. smaller volume of water can mean quicker swings in parameters (fish pee and poop) can mean amonia if there is not enough good bateria to counter act it.

get rid of the sponge and use filter floss it can be rinsed out a couple of times but i prefer to replace it every second water change just m/o