Total package weight 9.7Kg. Shell weight 9Kg. This is for cheaper carrier cost. 

This listing is for 9Kg clean native Oyster shell. Supplied double bagged.   The bag mesh is large enough not to clog and offers v. good through flow.  Every shell is hand scrutinized. All barnacle and tube worm removed. All protein hinges and clamp down completely removed.  Soaked for 24 hrs, rinsed in clean running water, then heated at 200 deg.C. for 60mins. The shells are high in exposed oyster shell calcite chalk. They are a general mix of sizes. The last pic. is Oyster shell calcite matrix.  

Taken from www.fishtanksandponds.co.uk  ``For every gram of ammonia oxidized into nitrate, 4.8 grams of oxygen is used, 7.14 grams of calcium carbonate is used``. This is bacterial demand only and does not consider the further depletion of carbonates from the hydrogen produced.

High stock. There is no doubt that sodium bicarb. `has its place` but why not try a gentler approach by using both, lessening the height of the `seesaw` effect and a first layer defence against a ph crash. 

 Get in touch if I can help with any questions.        Highlands and Islands carr. will be more. Please get in touch for actual.      I make no profit on P+P.

I also have bagged sea clams listed.