Frustrated with effluent rate on MTC ProCal Reactor

[ReefTank1]

I have had an MTC ProCal reactor on a 220 gallon reef tank (350 gallon total) for for a bit over 4 months now and the effluent rate has never stayed consistent. I started without a feed pump, just using a syphon feed from the refugium above the reactor. The flow rate dropped every time that I would set it. After a couple months of instability I even tried running a "Reef Mania" reactor for 2 weeks and had the same problem. So I went back to the MTC and started feeding with a Mag 2 pump with a pressure bleed off. No change. I have slightly closed the pressure bleed off line to pressurize the reactor and the flow rate still drops enough that I have to adjust it once, sometimes even twice a day. I have tried at different flow rates. I know this is an excellent quality reactor and have seen many great tanks running it effortlessly, and that's why I bought it, but I cannot keep adjusting it like this. I must be doing something wrong.

Current settings: 70mL/min flow rate, ~44bpm CO2, ARM coarse media

Reactor (flow rate looks high because bubble is in meter):
http://i187.photobucket.com/albums/x83/ReefTank1/P1050289.jpg

Top:
http://i187.photobucket.com/albums/x83/ReefTank1/P1050291.jpg

Regulator (works great):
http://i187.photobucket.com/albums/x83/ReefTank1/P1050298.jpg

Effluent drip and vent line:
http://i187.photobucket.com/albums/x83/ReefTank1/P1050296.jpg

Feed pump setup:
http://i187.photobucket.com/albums/x83/ReefTank1/P1050295-1.jpg

Flow meter (bubbles keep getting in this):
http://i187.photobucket.com/albums/x83/ReefTank1/P1050304.jpg

Lots of bubbles in media of first chamber, none in second:
http://i187.photobucket.com/albums/x83/ReefTank1/P1050307.jpg

This is my first reactor, so I am no expert. I have done some reading but nothing that I have tried has worked. My stony corals aren't growing as fast as they could because of this issue. I do have floating sediment particles and microbubbles in the sump where the feed pump is and will be installing filter socks this week, but the reactor second chamber is clear and I cant check the needle valve to see if it's getting clogged.

1. Can anyone suggest why this is happening? I am thinking it is either the needle valve or bubbles accumulating in the lines (however I looked today with a flashlight and there were little or no bubbles in the lines). I have heard someone suggest to eliminate loops in the effluent tubing but you can see above, due to the design of the flow meter and reactor I can't do that.

2. What is the solution? I really do not want to buy an expensive peristaltic feed pump and I have seen many people apparently running this reactor without one.

3. Do you think there are too many bubbles in the media? Do you think they are CO2 or from the tank water? If they are CO2 why isn't it dissolving fully?

Thanks a lot for your help

[Uncle Luke]

If i'm not mistaken, you're using the wrong media. MTC recommends crushed coral. Good luck

[hansmatt]

probably unrelated, but I have a MTC mincal where I had a similar issue, though mine doesn't need a feed pump. I had irregular/non-existent flow. I thought I had tried everything, when I took off the whole top assembly and soaked it in vinegar. I found there was a "basket trap" in one of the recirculation lines that was pretty much clogged with buildup. I removed & cleaned it, and voila, works like a charm with little/no adjustments necessary. Oh, and I just switched to the ARM style media too, after MTC said it would probably be fine but they had not personally used it.

[ReefTank1]

Thanks for your replies,

When I have time I will take apart the reactor to check for any flow restrictions. I will also install filter socks in the sump so the input water has less particulates and bubbles. I might replace the media with crushed coral.

Questions:

Is this feed pump setup ok? I know the owner of MTC recommended just using a syphon feed, which doesn't seem to pressurize the reactor. Does the reactor need to be pressurized at all?

What do you think the bubbles are that are getting in the flow meter and effluent lines? Undissolved CO2 or something else? There are absolutely no visible particles or bubbles in the second chamber where the effluent leaves the reactor, yet I am seeing bubbles in the meter all the time.

Thanks a lot for your help

[hansmatt]

My own minical is a siphon, not fed. I get no noticable bubbles in my two canisters, from external or CO2. The idea is that the CO2 gets dissolved & lowers the pH (as I know you are aware of already) but I'm sure that there are certainly some bubbles, but in my case too small to notice. I don't believe you want things pressurized at all from feed pumps, as you essentially get a little pressurization from the addition of CO2, and your setup appears to have a vent outlet to prevent too much pressure (?).
I did have bubbles in the effluent line on startup and until they get purged as they get displaced out of the canister by water.

[ReefTank1]

I have opened up the first chamber today and taken out the media. The sponge seems very clean and without obstructions. I think what is slowing down the flow is either the diffuser plate (fairly unlikely in my opinion) or more probably all of those bubbles between the media blocking the path of the water. It could also be the lines or the needle valve but it is very difficult for me to check all of those.
If the bubbles are most likely caused by excess CO2 then I think I will replace the media with fine grade ARM so that bubbles cannot be caught in those big gaps in the media. When I see people using MTC reactors they usually have fine media. Maybe coarse media just isn't meant for downflow reactors, I have only seen people use it on upflow models. Do you think the media change will work or is it not a good idea? Will bubbles still get trapped in finer media?
I have also put in 100 micron filter socks into the sump to lessen microbubbles. Should I put some sort of prefilter onto the feed pump as well or do you think the input water is not the problem?
I can't really think of anything else to do other than the media change and a prefilter.

Hansmatt, where exactly was the basket trap in your reactor? I am not seeing one in mine. Also are you using fine or coarse media?

Thanks a lot, hopefully this issue will soon be fixed and the input is appreciated

[hansmatt]

the basket trap is between the pump and the top of the cylinder along the horizontal tubing just before the 90degree elbow going down to the media cylinder.
I just changed to course media,

[hansmatt]

the basket trap is between the pump and the top of the cylinder along the horizontal tubing just before the 90degree elbow going down to the media cylinder.
I just changed to course media,

[hansmatt]

the basket trap is between the pump and the top of the cylinder along the horizontal tubing just before the 90degree elbow going down to the media cylinder.

[hansmatt]

oh, and just changed to coarse media, still works fine though, not evident excessive bubbles traped.