I recently bought an Aqua Medic Marin Control Digital specific gravity meter. Having used it over the last two months whilst setting up a new tank (I am new to Marines) I have had some upsetting news I'd like to share. Within days of stocking my new tank with crabs and snails (all parameters testing perfectly) I lost 95% of my stock. A conversation with a local supplier highlighted a problem with Aqua Medics digital SG meter. He tested over 6 of these modules and all gave false readings. He has since removed them from his shelves. He tested my water and although the meter consistantly read 34 ppt it was actually over 45 ppt! I'm now in the process of bringing my tank back to where it should be and initiating liason with Aqua Medic for financial re-imbersement. I'm just glad I didn't try to stock with anything more expensive from the start. If anyone else has had similar experiences please reply to this post.