Review: Aquarium Systems One and Only Reef Evolution range 


Nathan Hill looks at a new biological supplement for marine tanks from one of the biggest names in aquarium filter bacteria.

Nathan Hill looks at a new biological supplement for marine tanks from one of the biggest names in aquarium filter bacteria.

“Cycling a tank without test kits is like driving a car in the dark without headlights…” DR. TIMOTHY HOVANEC

I love Dr Tim. Not only is the man eminently qualified in bacteria, he knows how to translate filter knowledge into a form we can all understand (even me!) 

Timothy Hovanec, the man behind the Dr Tim’s brand (and who really is a doctor) was one of the pioneers of bacteria in filtration. He’s always been big in America (where he’s based) but getting his stuff in the UK was never easy. But now Aquarium Systems is supplying an original, authentic Dr Tim recipe, and suddenly the hobby is a better place. 

What makes it so special? Aside from the fact that pretty much everyone who uses it sings its praises, I love the transparency of Tim with what it does and how it works. 

The first thing you’ll notice with One & Only is that it causes clouding. If it doesn’t, you haven’t used it right. You need to shake the bottle vigorously before dosing. Dr Tim makes it clear (he has videos explaining stuff to this effect on his website) that the bacteria he cultures are grown on a tiny particulate substrate. When you add it, that’s what you’re seeing. 

One & Only claims to prevent new tank syndrome, but again, you’d benefit from watching his videos to understand the context. What he’s not saying (at least, I can’t find it) is that you can add this stuff to a tank with a load of fish and you’ll instantly have a mature set-up. Rather, what he advises is using the product to race through filter maturation using a fishless cycle. Used in conjunction with ammonia and a couple of test kits, this stuff kickstarts the biological aspect of your filter. 

There are caveats. If you’re running filter socks, or fine screens, Dr Tim suggests that they come out, as they’ll trap the particulates with the bacteria on, denying them a chance to reach the biomedia. You’ll also need, as he makes very clear on his personal website, test kits to monitor the whole process. 

The minimum dose on the bottle is 30ml per 100 l of water, though the packaging simply states ‘Best to use the entire contents at one time’, which isn’t going to be any kind of issue with a fishless cycle anyway. 

Oh, and I should make it clear that this version of One & Only Reef Evolution is a marine biological product. Not freshwater. 


There’s good reason this is the choice of biosupplement for public aquaria all around the world. The track record is great. Welcome to Britain, Dr Tim!

Price: £29.99 for 250ml

More info:, as well as