I have 3 cats and 1 open litter boxe with no problems regarding use or odour. I scoop once daily, and wash the litter pan montly with dawn dish soap and water in my bathtub. I also do not waste any litter at all, I never do a fresh replacement. Here's how I do it, and what I use: First I buy regular clumping litter, and lightweight litter and create my own mix. 1part lightweight to 3 parts regular clumping. I have a regular slotted litter scoop and also a mini straight edged plastic dust shovel (pan). This came originally as a broom whisk and dust shovel set from the dollar store. When it's time for scooping, i lift one side of the litter pan and shake /sift all the litter to one side of the box which exposes the pee clumps usually stuck to the bottom of the box. I take my dust shovel and scoop all that clump out, scraping the bottom to rid of any residue. Then I lift the box and shift the litter on the otherside doing the same, and so on until all the clumps are scooped and scraped out. I use the slotted scoop only for the poo, and any urine clumps that move freely.

When the box gets low on litter, I add more of both lightweight and clumping in the 1to 3 ratio. When it's time to wash the pan, i transfer remaining litter to a bag, wash the pan and add it back in.

What you do not want is to mix the pee clumps or have the pee clumps broken up and mixing with the clean litter. I find just digging in with a slotted scoop only breaks up the pee clumps and essentially mixes it in with then clean litter. This results in the pungent pee stink sitting and fermenting.

Give it try, hope it works for you. This way is life changing and saves money on litter costs! I only go through one 18kg box a month with 3 cats! The lightweight box lasts me about 3 months. No odour, clean, fresh litter, happy fur babies.