Hi all,
After reading online about it, i come to the conclusion. The blue stuff smells and the pink stuff create alge, then what about this solution:
Waste tank use odorless Bleach, yes i know it can destroy rubber like the seal. But the bleach will be mixed with water and not near the seal, bleach should be fine with plastic and does kill bacteria...
Flush tank use laundry detergent, since it mix well with bleach and creates a very nice scent similar to Fabric softner...