just wondering everyone's thoughts on these kind of products? do they actually work? any had any experience with them?
http/www.tetra-fish.co.uk/tetra/go/7B4FA824079E3BE3B2540904EC663F1D/?seite=6&group_id=302&group_2_id=12&lang_id=20
and
http/www.tetra-fish.co.uk/tetra/go/7B4FA824079E3BE3B2540904EC663F1D/?seite=6&group_id=310&group_2_id=12&lang_id=20
http/www.tetra-fish.co.uk/tetra/go/7B4FA824079E3BE3B2540904EC663F1D/?seite=6&group_id=302&group_2_id=12&lang_id=20
and
http/www.tetra-fish.co.uk/tetra/go/7B4FA824079E3BE3B2540904EC663F1D/?seite=6&group_id=310&group_2_id=12&lang_id=20