Used and Abused: JBL CristalProfi m greenline


Want to know how the products on sale really perform? We put them through their paces so you can sort the good from the bad.

Brand: JBL

Product: CristalProfi m greenline

Tester: Steve Baker

Test duration: 6 months

RRP: £36.45

More info:


Half internal filter, half Hamburg matten filter (HMA) – the JBL CristalProfi m greenline is an interesting piece of kit with a long-winded name. I shall abbreviate it to ‘m greenline’ for the good of further reading.


There’s a lot here for me to like. The sponge surface is large to emulate the an HMA filter, offering a gentle draw of water – Ideal for avoiding delicate fish and shrimps being sucked up by the filter. The sponge surface and a gentle flow also offer a good conditions for shrimps or fish fry to feed from, on collected waste particles and biofilm – as is the case for HMA filters.


The size, flowrate and pump unit make it familiar to anyone who’s used a ‘normal’ internal filter in the past and there’s plenty of space behind the filter to add media, such as ion exchange resins or a handful of bio-media.


A very simple clip enables the filter to hold a thermometer (this should be a common feature) and a small leaver on top makes the single suction cup mounting surprisingly secure. As ever, the JBL build quality is sound and it comes apart and goes together quite simply.


Then there’s the extension ‘m greenline module’ which adds yet more sponge and more capacity for other media. It’s a very simple case of taking a base plate off the main filter, clip the extension module on, and clip the base plate on to the extension. You can add two or three if you like, if you have a very tall tank.


The narrow, wide outlet disperses the flow nicely, again, suiting delicate fish and shrimps. It’s just a bit of a shame the outlet is fixed in position but it’s no deal breaker.


There is a deal breaker for me though. HMA filters are meant to be left, uncleaned, for months or even years. Allowing a more variable mixture of beneficial bacteria, Archaea, flagellates, worms and many other organisms which use the secretion from bacteria (biofilm) to fuel their community (biome). That’s the point of having a large sponge surface area and the surface area on the m greenline was sufficient to do this, with the added module, in my 70ltr tank. The problem – the deal breaker for me – is pump maintenance. I didn’t touch the filter until I noticed the flow slowing at around six weeks, then the whole thing has to come out just to clean the pump impellor – disturbing the whole filter.


A traditional HMA filter makes a mess of a tank when it’s removed – dumping filtered waste as you remove the sponge but this is very rarely needed. JBL have tried to address this by suppling blanking plates to put over the face of the sponges (for both the standard sponge and the modules). They are tricky to use, but it do make a difference.



If the pump was removed and replaced without disturbing the rest of the filter I would be raving about the m greenline from the roof tops. The fact that it doesn’t means it’s a hybrid that just doesn’t make sense to me – like breeding a Betta with a Hillstream loach producing in a fish that doesn’t like flow but needs well oxygenated water.


Ease of use: 2/5

Features: 3/5

Value: 4/5

Overall: 3/5