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Perhaps this is my own error, but these root tabs begin to crumble immediately upon hitting the water. This made it incredibly difficult to get the root tabs down into the substrate. Additionally, the water became quite cloudy after adding the tabs due to the rapid disintegration. I imagine if they were added pre-water it'd be fine, but post-water you will have quite the struggle.
They probably will work (they certainly wont hurt the tank) but the people who said they start to disintegrate immediately upon hitting the water were totally correct. You have to get them under the gravel ASAP. I cant imagine they last very long once they're in. I'll be trying a different brand or design next time. I mostly tried these because they are copper free so they are safe for shrimp. Also, Be careful taking them out of the packaging, they break easily.