MTC MVX Skimmer review

anit77

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FWIW, you can ignore everything on those charts above 15psi if you are going to be using the DCP18000. Shut-off is 30ft (12.9psi).

Thanks a lot for that. I didn't think to convert the feet of head to psi, it should have been where I started at ;). It's cool to see that based Jason's flow meter reading I was able to get pretty close to that number with Mazzei's charts and it shows that those flow numbers from them are accurate on the fluid side. I feel it also shows that removing the ball, spring and adapter from the air input really increased the amount of air pulled at that low of pressure.

I got my pump last week and got a good deal on a used FMK. So I started the plumbing while I'm waiting on the skimmer. Jeff called me yesterday and it will be shipping tomorrow. It will be interesting to see how my flow numbers compare to Jason's. There's a lot less piping with my setup. It's 1-1/2 off the pump to a long sweep 90 to get out of the sump, another foot of 1-1/2 before an adapter to 1", the flow meter and an adapter to 3/4, then the injector and finally the run into the skimmer. Total length of the piping will be about 5' to 6' with 4 plus feet of that being horizontal, with only two 90's. So the main restriction will be the injector and the water height in the skimmer body. It will be cool to see how that plumbing compares to 290/684 & 390/784 Jason is getting with the same pump.
 

anit77

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Leak test and vinegar bath. Going to build a stand for it tomorrow. Hope to get it online Sunday. Made a diy skimmate locker too.
6f650582c5ecc3b8ea91c006ac82339d.jpg
 

anit77

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I got it up and running last night and it started producing skimmate in 15min, just incredible.

It only have the 684 on it now, waiting on a pair of unions to arrive so I can slap the 784 in. I also ran into a problem with the FMM, the firmware on it is corrupted and it won't take a flash. Got a call setup with Neptune tomorrow. So I'll have no flow numbers till I get that resolved.
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anit77

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Well after a couple days I'm seeing my PH drop slightly each day. It's skimming pretty dang good but I don't think the 684 is enough injector for this height skimmer. I'm not seeing a nice white column of bubbles, it's kinda "Grey" like previously mentioned. The unions I ordered got miss sorted by UPS and I hope to get by them tomorrow then I'll get the 784 installed. With as much silicone Jeff used on the one I got from him I think it will be a PITA to try and get them apart. I hope the 784 is enough to handle the extra height. Otherwise I don't know how many options I have with 3/4" plumbing into the base. I'd have to figure out how to step it up to 1".

I also don't have any flow numbers yet. The FMM I got has a bad eprom. The firmware is messed up and it wont take a flash. I should have one by Friday night then I can see what flow I'm really getting, which will give me a better idea what's going on. I wish I had access to a Dwyer but I don't want to spend $100 on one just for this purpose.
 
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jason2459

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Great looking skimmer there. Any updates on it. Mines still beasting away skimming like a champ. Haven't touched it in about 8 months. Thank goodness for the neck cleaner. Ha!
 

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I think that it's the best bang for the buck purchase I've made for my system to date. I love the thing and it's so easy to clean. I can pop the cup off rinse it down and have it back on in 10 minutes. I've only done it twice since I've had it.

My setup is very similar to yours with the exception of running it external. I was surprised that with the piping I ran with it I couldn't get much more flow than you get. It runs at 390 to 410gph with a 784 injector. I just cleaned the pump last weekend when the flow dropped to 360. After that it was right back up. So after about 4 months it lost 10% flow.

I tried a 1" injector, 885 I think, and lost about 100gph. That was surprising as well. Being external and elevated above the water line in the sump must play a roll, along with the release of the pressure that came with the increase in injector diameter. The valve is very touchy too. The weight of the water in the vertical column... with the neck cleaner it's about 52" tall, the main chamber is 40ish inches. With that height and a 784 I can't get as dense of a bubble volume as your seeing, it still skims like a beast though. But adjustments on the valve need to be less than a 20th of a turn or there's a large change in the level.

Sometime in the future I may try a DCP-20000 or the next latest and greatest pump Jebao comes out with and see if it can create enough pressure with the 1" injector to get the flow back up. In the mean time I'll just let it do its thing, and it does it very well!

Also just wanna say thanks again. The detail you put into this thread made setting it up and dialing it in a breeze. [emoji106]
 

ca1ore

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I periodically think about using larger injectors on my MTC PowerPro. It currently uses dual 3/4" mazzei with a PanWorld 100 pump, but the effort to replumb with 1" pipe seems excessive so I haven't done it; plus my pump is native 3/4". I do have a PW 150 sitting round that is native 1" ...... hmmmn. FWIW, I have had the main reaction chamber extended as well.

IMG_0713.JPG
 
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jason2459

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You could easily try the 784 which is also 3/4" which would pull more air and some more flow. I'm not sure going up to 1" would be good. To much flow could happen.
 

anit77

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The DCP18000 excepts 2" off the pump. That's what I run on my return pump to a 2" wye where I split to the manifold and main return line.

On the skimmer I can't remember off the top of my head if i ran 2" or 1-1/2 off the pump. After the elbow coming out of the sump it starts stepping down to 1" for the flow sensor then 3/4" for the injector. When I ran a 1" injector it still connected to the 3/4" input to the bottom of the skimmer. But flow dropped to 290gph. This was confirmed by having to tighten down the valve to raise the level. Fluid dynamics isn't my strong suit but this really surprised me. I've also wondered if running 1" off the top of the pump straight through would make a difference. But like you I haven't wanted to mess with the pvc.

The pw150 has about the same max head as the dcp18000 so I dont know if going to a 1" injector will give you the same results I got. Jason's thought of going to two 784's might be the best bet.
 

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You could easily try the 784 which is also 3/4" which would pull more air and some more flow. I'm not sure going up to 1" would be good. To much flow could happen.

I haven't played around at all with swapping injectors. Can you give me the Cliff Notes version? I assume dual 784 would suck more air than dual 684?
 

anit77

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I haven't played around at all with swapping injectors. Can you give me the Cliff Notes version? I assume dual 784 would suck more air than dual 684?
I posted some charts above.

In a nutshell the injectors are very dependent on input pressure and fairly nonexistent output back pressure. At the same input pressure the 784 will pull more air than a 684 and should yield 100gph increase in water flow. But I'm not sure if that will be linear across dual injectors from the same pump.

I can only assume when I tried going to a 1" the pressure dropped on the input side of the injector and the water flow dropped. It did pull a little more air but not as much as it would at a higher psi and water flow.
 

anit77

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Post 198 has the injector charts.

You know, I'm a little slow sometimes... lol
The 3/4" input on the bottom of the skimmer is most likely was caused the reduced performance with the 1" injector due to back pressure on the output side. Without swapping that plumbing out it may just not work.

Stick with 3/4" injectors and 784 is as big as they go.
 
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ca1ore

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My PowerPro is due for an annual 'deep clean'. While disassembled, I'm going to add a port to allow the use of a bigger pump (PW150). I've got a pair of 784 injectors coming so will be playing around with the skimmer.
 
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jason2459

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Can't wait to see the results once the pump and injectors break in. Don't forget the remove the spring and ball as Jeff already took them out.

I need to clean mine out soon.... haven't touched anything in almost a year now. The MVX has been a workhorse with the jebao18000.

Having the skimmer turn off several times during feedings flooding the venturi has been keeping it clean. And the neck cleaner + Davie Jones skimmate locker has it on auto pilot.
 

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Subbed in dual 784 for 684 and PanWorld 150 for 100. A heck of a lot more airdraw and bubbles .... how that translates to performance remains to be seen. Encouraged though.
 
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jason2459

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May help or hinder pH depending on air being drawn. Running mine through co2 scrubber boosts my pH a good amount with the 784.
 

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Has made no difference to pH (air comes from outside). Initially I swapped the injectors, and kept the same pump. 784 actually performed worse than 684. Then I swapped out the pump and it's like a whole different skimmer. Far more air draw and dramatically better foam production.
 

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