Hydrofarm HGCOV6 Block Cover for 6 in Rockwool, 40 Pack

Rockwool Block Covers Keep Light Off the Media These covers sit on a 6 in rockwool block and keep light off the media. Algae on an exposed block competes for oxygen at the root zone and it is where fungus gnats lay. These covers sit on the block surface and take the light away, which removes the condition algae needs. Each one measures 7.0 by 6.5 in and is 0.2 in thick, so it overhangs a standard block rather than sitting short. The pack holds forty pieces. They are dual-sided: white on one face, black on the other. White goes up and throws stray light back at the leaves, black goes down and stops light reaching the media. A centre slot lets the stem through without crushing it at the collar. Shipping weight for the pack is about 0.33 lb. Hydrofarm list the item as HGCOV6. Fitting a 6 inch Rockwool Block Properly Block size is the thing to get right before anything else. This cover suits the larger block; the four and eight inch blocks take their own sizes and the three do not interchange. Fit the cover when you transplant the cube into the block, not weeks later once algae has a hold. Green already on the surface will stay green under a cover. Scrape it or replace the block first. The covers are rigid plastic, so they wash and go back on for a second run if you handle them gently. They will not fix a flood table that stays wet between irrigations. Standing water under the block grows algae from below, where no cover reaches. Drainage comes first and the cover holds the line after that. Key Features Pack quantity: Forty dual-sided covers in a single pack Cover size: Each piece measures 7.0 by 6.5 in and 0.2 in thick Two faces: White side reflects upward, black side blocks light downward Block fit: Sized for the 6 in block, with a centre slot for the stem Algae control: Removes the light that surface algae and moss need Reusable: Rigid plastic washes clean and goes back on next round Codes: Hydrofarm HGCOV6, UPC 638104945790, case GTIN 10638104945797 Technical Specifications Specification Value Model HGCOV6 Pack quantity 40 covers Cover dimensions 7.0 x 6.5 x 0.2 in Fits 6 in rockwool blocks Faces White one side, black the other Material Plastic Shipping weight 0.33 lb per pack UPC 638104945790 Case GTIN 10638104945797 Other sizes 4 in (HGCOV4), 8 in (HGCOV8)