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):

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Top:

Regulator (works great):

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Effluent drip and vent line:

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Feed pump setup:

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Flow meter (bubbles keep getting in this):

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Lots of bubbles in media of first chamber, none in second:

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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

 

[Billybeau1]

jdieck is our resident calcium reactor expert. He is not online at the moment but should see this within the next 12 hrs.

I'll PM him and have him take a look.

In the mean time, check out his calcium reactor calculator and see if it makes any sense.

Calcium Reactor setup calculator
http://home.comcast.net/~jdieck1/reactor.html

Good luck.

 

[Greg 45]

Read there instructions and follow them to a T. I gravity feed system. If you still have problems call them Leo is very nice and helpful. I run there pro cal and A HSA 3000. They know there stuff.

 

[jdieck]

Here are some ideas that you may want to explore:

a) Effluent needle valve: Totally closing a plastic needle valve wit a bit of force may leave a dent mark on the needle thus making it difficult to adjust the effluent flow. You notice this if the valve becomes very sensitive. A very little adjustment makes a large change in effluent and is difficult to adjust for a certain point of effluent. This issue is more troublesome with very small effluents at around 15 to 20 ml/min. so having said that I noticed that you are set at an effluent of around 50 ml/min, at that flow I doubt the valve will have any trouble though.

b) By the look at the bubbles on your first chamber, it seems the recirculation flow in the first chamber is very slow. THe flow usually carry the bubbles trough the media all the way to the bottom were the blue line at the bottom of the chamber will carry them back to the pump inlet.
The recirculation flow can be slowed down by certain factors that you may try to address:
+ Malfunctioning recirculation pump
+ Bottom media supporting foam too compressed or plugged with media. Try a firmer foam with larger cell size. Some Eheim canister filters have a (blue) round foam which is ideal for this reactor.
+ Other obstructions. Try removing the difusing plate or anything that is on top of media.

So any restriction to the recirculation flow in the first chamber may translate in low suction pressure for the recirculation pump thus reducing the pressre to the second chamber.

c) A plugged line. Sometimes a bit of media gets trapped in the flow meter or even bubbles in the effluent line if it forms an inverted U can obstruct the effluent flow when the pressure is low.

d) Try increasing the diameter of the feed tubing from the mag drive to the recirculation pump. You can replace the John Guess conector at the recirculation pump inlet to an insert then use a 3/8 or 1/2 " hose to feed the reactor.

 

[tmz]

Just a thought. Could your pump be pushing in microbubbles from your
sump?

 

[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.

Questions:

Is this feed pump setup ok? 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?

Is the media that I am using the problem? I am not sure which brand is best or whether to use coarse or fine media. I think MTC and someone in the equipment forum recommended crushed coral. I would like to know if the coarse ARM media should be replaced before i take apart the unit.

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

 

[jdieck]

<a href=showthread.php?s=&postid=13153927#post13153927 target=_blank>Originally posted</a> by 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.

Questions:

Is this feed pump setup ok? 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?

Ingeneral, increasing the internal pressure in the reactor increases the solubility of CO2 which improves performance

Is the media that I am using the problem? I am not sure which brand is best or whether to use coarse or fine media. I think MTC and someone in the equipment forum recommended crushed coral. I would like to know if the coarse ARM media should be replaced before i take apart the unit.

The media is OK, I recommend large sized media in the first chamber (To increase recirculation flow) and small grain media in the second chamber (To increase area of contact) but in your case the second chamber is large enough that any size media works well.
ARM media IMO is one of the best dissolving medias.

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.

Most probably excess CO2. Bubbles seem to accumulate in the first chamber because the flow is dounwards, against the tendency of the bubbles to rise). In the second chamber the flow is upwards (with the bubbles) so it is easier for the bubbles to come out to the effluent and trough the flow meter. In any case the bubbles should not get trapped in the meter, they usually just pass trough it very quickly, rise the black ball and then it drops back to the metering position once the bubble is thru.
Try increasing your effluent to around 80-90 ml/min and reduce the bubble rate to 30 bpm.
The PH in the first chamber in this reactors is difficult to get below 6.5, they have good dissolution which works against lowering the PH. If you try to run it below 6.5 you will need excess CO2 which will form the bubbles.

Thanks a lot for your help

 

[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.

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

 

[jdieck]

I doubt changing the media will have any effect on the bubbles, I have tested both small and large media in downflow and they both work properly. Try insuring that all air inside the reactor is properly purged before turning on the recirculation pump.

 

[ReefTank1]

Thanks for your reply jdieck, the amount of bubbles in the chamber keeps increasing over time (and the flow decreases). Whenever I completely purge the air out it keeps filling with the bubbles again.
If its not the media then I think the excess bubbles accumulating in the reactor and slowing the flow must be caused either by excess CO2 or microbubbles getting in the reactor. I don't see why it would be CO2 because I am running the reactor very lightly, but I will test the effluent pH and maybe reduce the bubble rate and increase the effluent rate. I'll also wait for the microbubbles to decrease with the filter socks (which seems to be taking a very long time). Hopefully the problem is being caused by one of these things.

 

[Floridiot]

<a href=showthread.php?s=&postid=13227482#post13227482 target=_blank>Originally posted</a> by ReefTank1
Is the media that I am using the problem? I am not sure which brand is best or whether to use coarse or fine media. I think MTC and someone in the equipment forum recommended crushed coral. I would like to know if the coarse ARM media should be replaced before i take apart the unit.

I've used the large schuran type media in a ProCal I used to own, and it worked fine. If for any reason you want to sell your ProCal, I'll gladly buy it from you for a fair price.

 

[gkyle]

What about the quality of the effluent valve itself? I have the same issue with my GEO reactor; I replaced the John Guest effluent valve with a different type that's slightly more precise. Even then I had to add a secondary pinch-type flow restrictor to get it to stabilize a bit. Turning off the recirc pump and purging the air as mentioned above has helped also.

Are there any quality needle valves (like the one on the CO2 bottle) that will work with saltwater?

 

[ReefTank1]

I have tried running it for a couple days without CO2 input and set at 30ml/min after purging all of the air out. The bubbles are not showing up anymore but the flow rate dropped to 20ml/min within 24 hours. The reactor is pressurized at 3psi (I closed the pressure bleed off line on the feeder pump). I thought that this would help in preventing any buildup that would slow the flow, but apparently something is still gradually slowing it down (although not as fast as when CO2 was being injected).
I checked some of the lines when I took the reactor apart and they were clean. I also added ZeoMag granules if that means anything.
So the overall cause of the original problem was a combination of too much undissolved CO2 and whatever is currently slowing the effluent rate. Any ideas as to what the cause of this might be? Should I just keep opening the valve to 30 when it drops and maybe the problem will go away? I want to make sure the flow is stable and the problem is eliminated before I start adding CO2 again.

Thanks

 

[gkyle]

Interesting, I have the same issue and also recently added Zeomag.

 

[jdieck]

Unless the zeomag is releasing small particles that might plug the effluent valve I doubt it is it.
Try opening the valve back to 30 ml/min every time and at certain point it will stay there.
Alternatively you may want to replace the effluent valve.

 

[ReefTank1]

I will keep resetting it at 30. However I am finding that to run the flow at 30ml/min I have to turn the needle valve to a nearly closed position, and I get some resistance when closing it down like this. Is my pump (Mag2, 250gph) too large? I have closed the pressure bleed off line so all of the flow is going into the reactor because I heard that pressurizing the reactor increases dissolution and will help in avoiding a clogged valve.

Thanks

 

[jdieck]

<a href=showthread.php?s=&postid=13288541#post13288541 target=_blank>Originally posted</a> by ReefTank1
I will keep resetting it at 30. However I am finding that to run the flow at 30ml/min I have to turn the needle valve to a nearly closed position, and I get some resistance when closing it down like this. Is my pump (Mag2, 250gph) too large? I have closed the pressure bleed off line so all of the flow is going into the reactor because I heard that pressurizing the reactor increases dissolution and will help in avoiding a clogged valve.

Thanks

The pump may overheat if limited at 30 ml/min. Even with the bleed offf valve in the feed line open there will be enough pressure in the reactor for it to be efficient.

The needle valve almost closed is part of the problem specially if the needle has a mark from having closed it a bit tight. Lowering the reactor internal pressure a bit will allow for the needle valve to run more open.
Also you could increase the effluent rate (say to 0 ml / min) to run it more open and to compensate for the increased addition you can run the reactor at a higher PH value. In this mode you will be adding more effluent but with less alkalinity content but the combination will end up adding the same total amount.

To do this just set the effluent to 50 ml/min keeping it there while playing with the reactor PH by changing the CO2 bubble rate until the addition matches your consumption.

 

[ReefTank1]

Thanks jdieck, I have set it at 50 and opened the pressure bleed off completely. There is still some resistance. What happens is if i start closing the needle valve slowly from open, when it gets to about 70ml/min i encounter resistance and it stops decreasing. I have to turn it slightly harder to bring it down lower than that. I will let you know if the flow continues to decrease from 50.

gkyle, did your ZeoMag form a pile of white powder at the bottom of your reactor?

Thanks for your continued replies

 

[jdieck]

By your description it seems the needle valve may be damaged.

 

[ReefTank1]

Ok so is it safe to assume that the needle valve is what has been causing this entire issue from the start?

If so, I have no idea how that happened, but I will call MTC. Do you know if this is this an expensive or hard to acquire part?

Thanks a lot, maybe we have finally found the problem