One-time Purchase is Used Slowly,Express delivery Arrives in 5 Days,32pcs Filter Harmful Gases，Aquarium Cube Filter, Activated Carbon Aquarium ​for Ponds,Fish Tank,Stock Tank for Horse

Bought these after seeing a Reddit post which explained their use as a replacement for the carbon filter cartridge present in some resin printers. Was able to easily cut the carbon block to size and install it in my printer - no more resin fumes in my room anymore!Judging from my experience with how long each filter cartridge lasts (around 3-4 weeks before the odor is noticeable outside the printer), this pack of carbon blocks should last a little over a year in printers like the Elegoo Mars 2 Pro.As a side note, this is likely a *terrible* way to filter water, especially if merely placed at the bottom of a water tank. If that is your goal, buy granulated activated carbon instead, construct a container for it, and flow water through the carbon with a pump.

I like that the package came quickly. What I didn’t like was the fact the cubes did not work as stated. In 3 days the water got murky and did not get cleaner. Water through has to be scrubbed and refilled with fresh clean water in less than 7 days. Again cubes were placed back in tank but same results even after 2 more cubes so a total of 4 cubes in a water through holding 100 gallons of water. The cubes did not keep the water cleaner than 2 to 3 days. Afterwards water was murky. Cubes were cleaned with mild soap and water as suggested but after a week, about 5 days they started to crumbled. One fell apart in my hand as I was rinsing it with water. I DO NOT RECOMMEND these cubes.

This is my second order. The first cubes I ordered held together and lasted a full season. They helped keep the water troughs clean. Although is also keeps the water clean, the new cubes are half the original size, brittle and broke up into pieces within a couple of months. I'll go back to the large cubes.

I bought the 4 pack of these charcoal blocks to help keep our horse’s water trough cleaner. I put 2 in the trough and waited a couple days and put the other 2 in and that seemed to be the ticket. They are washable and reusable. Would recommend Ann’s will but again when needed.

I wouldn't purchase againDoesn't keep trough clean like it statedNot worth spending moneyQuality parts of it was broken off