NorthernCF: nice observation
H.a.Z: Nice idea to make hotel and frag tank, two in one! How do you make water inlet and outlet? In the shot i have not perception. If you were two months ago in Lisbon we could talk and you might see my prop place.
Fatrip: As stephencraig suggests, you can find diverse similar products in your country. Take a look on online too. Biodigest and Bioptin (Prodibio products) make the same effect. I prefer these than Zeovit products because there is no way to know composition of last ones (Mysterious…may be dangerous!) is only my opinion...of corse.
Cheers,