JBL CristalProfi e402 GreenLine

JBL CristalProfi e402 GreenLine is the smallest external filter in JBL's CristalProfi e range, for aquariums of 40 to 120 litres. An external filter holds far more media than anything that fits inside a tank, and it does it in the cabinet where you cannot see it. JBL rates the pump at 450 litres an hour.

Key Features

• For aquariums of 40 to 120 litres: JBL's figure for this model, and the first thing to match before anything else.
• 450 litres an hour pump: JBL's rated output. In practice you will see less once media and hose are in the way.
• Quick-start priming button: the filter primes itself at the push of a button instead of you sucking on a hose, which is the job everyone dreads.
• Patented pre-filter: JBL's pre-filter catches the coarse dirt first, so the biological media behind it stays clear for far longer.
• Closed water circuit: the water leaves the tank, goes through the filter and comes back, which is what lets an external hold so much media.
• 100% more pre-filter surface: JBL's claim against its previous generation, and the reason media exchange is quicker.

Setting Up An External Filter

• The filter body has to stand below the water line, in the cabinet rather than beside the tank. An external filter is a siphon with a pump in it, and it will not prime above the water.
• Keep the hose runs as short and as straight as you can. Every extra metre and every tight bend costs you flow.
• Check both hose connections and the head seal before you switch on, then look again an hour later. Leaks show up on the second check, not the first.
• Never let it run dry. A pump with no water in it will destroy its own impeller and shaft in minutes.
• Put the coarse foam first in the flow, the fine foam after it and the biological media last. Fine media placed first simply blocks.
• Keep a towel and a bucket under the cabinet whenever you open it.

Good To Know

• A new filter has no bacteria in it. Stock slowly over the first weeks, feed lightly, and test ammonia and nitrite until both read zero. A filter becomes a filter over about a month.
• A pump's rated output is measured with nothing in the way. Media, hose length and height all reduce it, so the figure on the box is a ceiling rather than what you will see.
• Rinse filter media in tank water, never under the tap. Chlorine kills the bacteria that do the biological work, and that is most of what a mature filter is worth.
• Service before the flow drops noticeably. By the time you can see a filter struggling it has already stopped doing part of its job.
• Never replace all the media at once. Change one stage at a time with a week or two between, or the tank can cycle all over again.
• Switch the filter off at the mains before opening it or putting a hand in the tank, and fit the cable so water cannot run down it to the socket.
• JBL gives a two-year guarantee, extended by a further two years if you register the filter with them.
• Service the pre-filter more often than the rest. That is the stage doing the dirty work, and keeping it clean is what keeps the biological media working.