Filter, Apollo Bio Filter

Filter your own gas
We often take our air supplies for granted, but they rely on good compressor maintenance and regular filter changes. Its not always like that. Anyone who has had the dubious experience of an oily fill will know that awful feeling of gagging and retching that can accompany it.
     In the days when I had my own air-station in a Mediterranean resort, I like to think we ran things impeccably, but I made the mistake of visiting another dive centre and got a bad fill after a dive with it. Even though I was able to drain down the tank and refill it with clean air as soon I discovered what Id been given, the taste lingered on.
     The owners of the other dive centre denied giving me a generous helping of oil and were, presumably, equally surprised one day when their compressor exploded in a thousand and one pieces inside their compressor room. You can compress air but you cant compress oil!
     Nowadays I tend to use rented tanks. If I get a bad fill, I simply ask to swap it for a better tank and leave the owners to sort out the problem. Thank goodness most compressor-operators do the job properly. But that is not always the case and it is not always in the third world that problems arise.
     The people at Apollo, in Japan, feel that the problem may be more prevalent than it probably is. They have introduced a personal breathing-filter, the Apollo Bio-Filter.
     This screws in-line between the regulator first stage and the hose to the second stage. It takes the form of a nicely machined bit of aluminium that contains an activated-carbon filter at one end and a large foam pad to which one can add water at the other. The carbon filter removes taste and the water-soaked pad is there to moisturise the air that it is assumed has been properly dried in the process of compression. So, no more dry throat during a dive.
     That seems like a good idea, doesnt it But then we come to the practicality of using it, which is where this, like a lot of good ideas, falls down. The first thing that became apparent to me was that once in place, the filter formed a perfect handle by which the ill-informed might attempt to lift a fully-kitted tank.
     There was also the unexpected problem of primary hoses having a different thread diameter to other low-pressure hoses, so it wouldnt fit unless I used the alternative second-stage hose.
     Consider too the cost of the activated-carbon filter cartridge, which needs to be changed for every few hours of diving, and the fact that the moisture pad needs to be kept clinically clean, while the water added to it should be pure too, if you dont want to swap one problem for another. So instead of filtering out a problem after it comes out of your tank with your air, why not concentrate on seeing that the problem is not there in the first place
     If you get your tank filled regularly at the same place, Im sure youll be quick to tell the compressor operator of a problem. You wont want your tank contaminated, because it might well stay that way, Bio-filter in place or not.
     If youre away in a strange place, refuse to use a tank with air that tastes funny, and if it starts to taste funny halfway through a dive, end the dive immediately.
     A properly run compressor will not give you flavoured air and, thanks to the prevalence of nitrox installations with double-filtering, thats getting rarer. If a dry throat is a problem, I suggest you drink plenty of water prior to diving. It seemed to cure that particular problem for me.
The Apollo Bio-filter costs £95.95, replacement filters £6.

  • CJ Evans International 01258 451269,

  • Divernet
    + Filters out taste and puts back moisture

    - Something you should not need
    - Makes a handy but dangerous handle