EcoBio-BlockStone for Aquariums, Small - Biological Water Clarifier and Odor Remover, Maintains Healthy Clear Water. Treats 4 to 20 Gallons

My water was crystal clear before I put this rock in. I soaked it for a week, changing the water, before I put it in the tank. This is my water after changing the water & cleaning the filter for 2 days. Terrible decision!

I tried everything to get my betta fish tank clear and nothing worked. Within 2 days of putting this in it finally is crystal clear. I wish I found this sooner.

Guys, this cube is fish tank life hack!!!My almost dying cloudy water fishtank went to crystal clear angelfish home for babies in just 3months! It was so calming to see the whole fish tank heal and be healthy to the point they decide to have babies. The water is always clear and my fish tank stats never change even in a month! This makes my fishtank maintenance come from chore to relaxing once a while thing! This is incredible and so easy to use, just wash it off and leave overnight, place it in and sit back and relax! Totally recommend! Wow!

I followed instructions (rinse with chlorine-free water, soak in chlorine-free water) and put the block in my tank below the filter.24 hours later, my poor fish were floating near the surface and barely moving.I quickly went to test and found the Ph in my water went from 7.2 to over 8.9. (my API master kit only goes to 8.9.... the color was beyond dark purple where the scale ends).I tossed some "pH down" in.... and performed a 50% water change. Eventually, with some more "pH down" got the pH back to 7.4. Couple hours later the fish seemed ok, moving around normally.For now I have this block out of the tank.I'll try again later, as so many people seems to benefit from it.... but will closely monitor pH when I do so..Giving it 2 stars for now, but may update later if things improve.Also, after removing block my pH stays a constant 7.4 (checking every day for 3 days)My $.02Update: pH was 7.4 when I put the block back in yesterday afternoon. Last night it was 8.5. This morning its above 8.9 (my high-pH test solution tops out at 8.9, but it was much darker than that. I put some acid solution in to bring the pH back down to 7.4. Hopefully this will balance out eventually.Update 2: Last night pH above 8.9 again, did water change and some more acid solution to get pH down to 7. This morning I checked and it was back to above 8.9 pH (my API high-range pH test only goes up to 8.9). Did another partial water change+acid solution and got pH back down to 7.5. I've about had it with this sh*tty block.Update 3 (final): I give up. With the block in the pH goes from 7.2 to well over 8.9 within about 12 hours. If I remove the block, pH stays steady. I've been dosing "API pH down" for days now, but plants and fish are suffering so I'm pulling it out to return.My tank is an established 10gal tank with plants and a few small fish.Maybe the block is "bad" but I just don't care at this point... bad product and no way to contact manufacturer far as I can find

I've used this in both my larger cold-water tank (30 gallons) and in my 10- and 6-gallon tanks. These are great at maintaining water clarity, reducing ammonia, and helping keep the tank inhabitants happy. Yes, they are kind of ugly, so I hide them behind foliage in my planted tanks. And yes, you will still need to properly cycle and maintain your tank water quality. Overall, though, I find they do a really nice job of reducing the frequency of water changes and keeping the tank water crystal clear.These are particularly good at clearing up cloudy water in planted tanks with substrate, and I've used them extensively that way to strong effect.