Clearseal 100cm drop-off aquarium is out in the wild

Long established British tank manufacturer Clearseal is now shipping its new drop-off tanks to retail stores.

First shown at the Aqua 2019 trade show, Clearseal is the first of the British builders to produce a stock, off-the-shelf, repeatable drop-off tank of a decent size, and after getting to touch one last weekend I can confirm it’s pretty exciting.

There isn’t much variation you can do with five panes of glass. Long, thin, wide, shallow, tall, braced, braceless, peninsula, we’ve seen and done them all, and all have their individual merits for individual fish, set-ups and situations.

But add a sixth and seventh pane of glass and a step, and suddenly comes a whole heap of inspiration and aquascaping potential. For both freshwater and marine.

Drop-off peninsula

Clearseal actually debuted two drop-off tanks at Aqua – one with a rear corner weir and one with a centrally mounted side weir which enables the peninsula drop-off to be viewable from both sides.

The latter is my personal favourite and clearly the favourite of others too, as I’ve seen three of these cool looking tanks on display in my area alone.

The tank is rimless, with neat black silicone and is 1000 x 457 x 600 mm high. 600mm is the deep part and the step is at about a 60:40 ratio along the length of the tank.

Putting the drop-section that far down the tank also enables the first cabinet cupboard to house the supplied sump and the weir is drilled with three holes to accommodate the classic Herbie Method pipework configuration.

The sump is basic in design and smallish (it has to be,) but a reefer will put his/her choice of filtration in there anyway, and every reef keeper differs in their own personal ideal sump design.

The cabinet comes in five colours – white gloss, oak, grey gloss, dust grey and graphite gloss, and comes without equipment for the user to populate the system with their own kit preference.

Although I photographed this one at Aqua with a single luminaire on it I and most other people would probably put modular LED lighting on it, enabling truly different spectrum and intensity in the two different areas.

I’d start with zonal lighting and go extra blue for the drop-off section and whiter for the shallows, or maybe set both lights the same and let the natural PAR drop-off do its thing, and place corals accordingly.

I ran a smaller drop-off once for some territorial marine fish and they utilised the different areas too. Each one calling either the shallow bit or the deep bit home.

But the potential isn’t just there for the reef guys and I’ve seen one set up as an aquascape already. For me, if it was freshwater, I’d go Lake Tanganyika and again utilise those different zones to me and my fish’s advantage.


The 100cm model is the only one in the range at the moment but hat off to Clearseal for building it. Drop-off tanks are a nightmare to design and build as that unequal weighting causes massive stress on the tank, and the cabinet must also match and distribute that weight perfectly.

The internal step features an extra strip of glass for strength and stability and that cabinet has not one but two vertical boards propping the tank right at that critical load-bearing point.

The other advantage with that split internal cabinet is that it enables a wet cupboard – the big one with the sump in, and a smaller dry cupboard. All reef tanks could do with separate dry cupboard for electricals as dosers and controllers are such a big part of the hobby. Regardless of tank size.

In a perfect world I’d like a larger 120cm model as well, and with an even more pronounced drop-off, but glass thickness and cost are probably at play there, as well as the obvious physics.

The 100cm model is being sold for around £1395, which I think is reasonable for such a novel tank design. And it offers something truly different (in terms of shape,) in the rimless reef tank market.

I love imagining what a new fishkeeper must make of it when they first clap eyes on one. I bet they never knew you could get such a thing. You can now…and this marine modernity has come from one of the oldest tank building firms in the business.

More info at J&K


Jeremy Gay

Author of three fishkeeping books and lifelong fishkeeper. Experience includes editor of Practical Fishkeeping magazine, editor of Pet Product Marketing magazine, multi award- winning livestock manager and aquatic store manager.