Ok guys...need ur expertise! I have a fully cycled 20 gal aquarium. With a couple Cory's, a few Platys, a few lyretail mollies and a couple mystery snails. My parameters are great, been doing 30% water changes weekly. I have a Top Fin Cartridge filter in that tank and in my 5 gal with my betta only I have a Marineland cartridge filter. I just did my first cartridge clean tonight. I followed y'all's advice on not tossing my cartridges but instead rinsing them well in the old tank water. Got lots of nasties off...really looked good after. However both my filters show red on the indicator to (change filter) still. Is this bc the old carbon is still in there? I thought as clean as it came the change cartridge indicator would go back to green. It's a ton cleaner than it was. Everyone is happy and healthy...stupid filter cartridge indicator just stays on red/Change. What u guys think?