May i ask what physoing is? A diotom filter just clears up the water further than your current filter can by taking very small impurities out of your water. It doesnt take place of water changes or anything. It isnt a filter run 24/7 its run once every 2 weeks or so for a couple hours to clear up your water. The cheapest ive seen one is the Whisper Diatom from Dr Fosters i believe for around $80 for the unit not replacement powder bags or cartridges.
- depthC