Ca reactor advise

[andestang]

Just getting ready to put my ca reactor on line. Its a dual chamber (mocalc 300/austin oceans) and I've never run one before (always used Kalk) I've been running fresh water through it from a five gallon pail for about four days now(bought it used and the media was left in it for a few months) I get air bubbles that build up at the top of the main chamber and form into a larger one and when it gets to the intake tube that goes down to the pump it of coarse effects the flow and is noisy. I'm worried its going to air lock the pump. I've tried a few times to bleed it out(have a PH probe addapter plug on top), but awhile later more bubbles just form. Any tricks to getting the bubbles from forming on top or is this normal ? I'm also assuming that after the air goes through the pump that most of it will go through the chambers again and won't go out the effluent line.

[Delphinus]

You shouldn't be getting air, but I wonder if this is a function of running it in FW. Usually you get a little bubble form when first starting up and over time it dissolves into the water or gets blown out the effluent.

Generally speaking you can get a little CO2 bubble form but it is OK for this to pass into the pump intake (it's what you want, actually). I think the Mocalc's are upflow which explains why there isn't a recirc line, a good downflow reactor will have a recirc line just so that the CO2 bubble can get sucked back into the pump intake.

For the pump to vapour lock it would take something seriously wrong like a complete blockage.

[andestang]

I was hoping you were lerking out there Tony I will be switching to a salt mixture tonite. Not adding any CO2 yet. I was also wondering if there is some sort of chemical reaction going on because of the media being used.I seem to remember reading something about running a reactor that has sat for a period of time and not to hook it up to tank till its been run for awhile as it would be lethal.(can't remember the name of the outcome from chemical reaction, I'll have to go search it out )

[Delphinus]

What media is it and how old, do you know?

If the media was sitting wet I'd give it a good bucket flush before using, but otherwise just a good few rinses to get rid of most of the powder (the media breaks down over time). Assuming it's still usable though - I've found it's generally best to replace media (if it doesn't get completely used up) after about a year. If you compare old media to new media, the new stuff will have a lot more "granular uniformity" (is that a word?) and the older stuff will feel "soft". In an upflow/fluidized reactor it will probably get used up more but in a downflow reactor the mixed grain size will lead to compaction making it harder for the pump to pump through (and you may get cavitation in that case). I'm not sure if old media can leach more phosphate than new media but that might be something to watch out for.

I don't think you get those problems with the Schuran style media now available (much larger pieces). I haven't tried that yet as I'm sitting on a few containers of ARM I figure I should use up first before switching. I think for those you need to run your reactor at a much lower pH though.