been using these on my tropical tanks for over an year now 100% great, only a dig the cartridges a bit on the £ side as well for any spares. but well worth the money. tropical or marine.
the catalyst last around a year about £11 or £12 a time from MH . the review that was given is way out of date and don't give it justice and the science is their. great customer service from the manufactures .QIAN Hu is the guy to speak to any problems he will sort it out for you.