CerMedia MarinePure Block Bio-Filter Media for Marine and Freshwater Aquariums, 8 by 8 by 4-Inch

Great product. Must for marine aquarium. I have seen many videos of abroad using it

Being a Microbiologist, I thought these MarinePure ceramic bio-spheres were a great idea with their vast surface area for bacterial colonization. But my excitement quickly turned to skepticism when I noticed they were covered in a ceramic grit right out of the box. I thoroughly rinsed them clean in the sink and put them in a large bucket of aquarium water. They soaked for a week. When I drained the water out to put them in my tank, I noticed more grit on the bottom of the bucket. I did this 2 more times for a grand total of 3 soaks. Every time the bottom of the bucket contained grit.Bottom line is that these ceramic bio-spheres rapidly break down into an abrasive ceramic grit. Since these would be after my mechanical filter, this grit could be discharged downstream into my wet/dry filter containing PLASTIC bio balls, pump chamber and pump, discharge orifices and finally the tank.This abrasive grit would eventually start plugging things up and possibly wreck my pump. And the little Corydorus catfish, who like to suck everything up in a form of filter feeding most likely would be injured by the abrasive grit. And the abrasive grit would scratch up my acrylic tank should some of it wind up in the pad I use to clean algae from the inside tank walls. Abrasive grit in your Aquarium isn’t good for anything.Plastic bio-balls may not have the surface area, but they don’t plug and they certainly don’t break down. This product is a great idea, but it needs to be re-engineered and chemically stabilized so it doesn’t break down in your filter and spread abrasive grit through your system.I feel I averted a catastrophe by doing an extended check of this product before using in my tank. It will be returned.

This is a fantastic product. I put these in one of my sump baffles and let the tank cycle for about 6 weeks. Then I tried to spike the ammonia in the tank with flakes, mysis shrimp, uncooked jumbo shrimp, a chunk of walleye and even a shot glass full of clear ammonia and I haven't been able to get a positive ammonia test result. I thought I was doing the testing incorrectly but two LFSs confirmed that there was ZERO ammon-sies in the water.The picture is kinda crumby with the red plant light in the fuge, but you can see the placement of these orbs. It works like a charm.This is the fuge light, btw. This thing performs way better than I'd expected. My fuge grows so much chaeto that it's almost annoying.https://www.amazon.com/gp/product/B00GNWK2XO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

This is my second box for my BioCube 14 that I added a 10 gal sump to.So I have one gallon of these in the sump, enough for 500 gallons per the manufacturer. My tank is testing at zero ammonia, nitrite and nitrate. I have only done one water change after the tank originally cycled in February. I feed one cube of frozen food daily to the three Chromis and have yet to get nitrate to register on my test kits.I know the chaeto in the refugium is helping but I know these balls are working.

I saw many have this issue where the plates arrive shattered because of the fragility and those shipping it not handling it with care. I was hoping not be one of the unfortunate souls who opens the box to find it broken to pieces but I was. This is such a disappointment.

The block is broken into three large pieces with thousands of little “crumbs” from the broken pieces. The blocks will still work so not trying to be picky but for 30 bucks I would like one solid piece I can slide into my sump and remove easily in one piece. Not worth the effort sending back and waiting on a new one. Guess I’ll just deal with my crumbles and throw the crumbs away.