DrTim's Aquatics Reef Safe Waste-Away Time Release Gel – Natural Fish Tank & Aquarium Leave-in Waste Management Solution for Dissolving Cleaning Organic Sludge - 2 Pack Treats 200 gal

I've been using these for 1.5 years now. I have these in all of my tanks, and change every 3 weeks with new ones. I also supplement with the liquid version.The reason I use these is to lower nitrates. They are effective at doing that if you stay on top of renewing the strips. If you have persistent issues with nitrates, consider every 2 weeks adding liquid version in addition to strips. You have to be super careful when adding liquid. Only use 1/3 dose first. I then add more gradually every 24-48 hours until the tank gets a LITTLE cloudy. The cloudiness indicates a bacteria bloom, which is what you want to really lower the nitrates. Make sure to use your protein skimmer upon cloudiness to augment oxygen. You can use the skimmer without cup if you don't want to remove bacteria. But be careful as a bloom without strong oxygen input will kill your livestock. So either don't augment with liquid or make sure to have oxygen input to be successful.Be patient at first. I thought it wasn't working at first, but it takes time to build up the bacteria population. At first, use liquid as directed and make sure to have strong oxygen input. Then add strips to maintain that bacteria level. It took about 7 weeks to start seeing decreases in nitrates.This product has saved me from giving up my giant tank! All parameters have been good except nitrates kept creeping up requiring a significant water change. I don't mind water changes on smaller systems, but it is too much work to make water and change frequently for very large tanks. These strips and the liquid version honestly saved me from giving up my giant setup!!I don't know about the product cleaning up gunk...but I do track my parameters and I know they reduce nitrates and help maintain lower levels for longer. I now only partially change water in the giant tank every 3 months, rather than every 2 weeks without the product.

First month I didn't notice nothing but after the 2nd month started to notice my tank being cleaner not needed to do water changes

I have been using this for a while. It works very well when trying to lower Nitrates in a reef tank. I highly recommend it!