Deer Run Hobby RO—Please Share Your Experiences and Ideas

[maple marc]

I bought a Deer Run Hobby RO unit at the beginning of this season—first experience with RO, so I’m learning as I go along this year. This unit has met my needs well, with my 118 taps and an average sap run of 250-400 gallons. I wanted something that could feed my 2x6 Leader WSE evaporator (25-30 gph) on the fly so I didn’t have to RO overnight. My sugar shack is unheated. The RO on a dolly works great for me—I can roll it in and out of a nearby heated shop, into the sugar shack for processing as I collect in the morning before a boil. It also seemed like a great bargain compared to other comparable units.

This model has one 4x40 membrane, a 10” pre-filter, a ¾ hp pressure pump that powers a Procon brass pump. The lack of a supply pump requires gravity feed. The manual says to operate it at 225 psi. It also has a built-in 5 gallon stainless rinse/wash tank with some valves that can be reversed for recirculation. Most of my sap is around 2%, and with one pass I usually can get to 4%. I remove 30gph of water. A second pass gets it to 6%. I’ve developed a system where I collect in the morning and after I have the first 55 gallon load in the sap tote I start to recirculate it through the RO. I continue to add collected sap to the tote, directing permeate to another tote. It usually puts out about 30 gallons of permeate per hour until the concentrate gets higher and it slows down. The highest I have concentrated so far is 9%.

When I have some high concentrate I direct it to my head tank that feeds the evaporator—usually about 30 gallons. When I finish collecting I start to boil and continue recirculating the sap tote through the RO. When the head tank gets low I redirect more concentrate up there.

This system has worked well, although there are some problems. I noticed during my first operation that the hose between the pre-filter and the pump was collapsing a bit, and I could see air bubbles. The pump made more noise with more air bubbles, especially when the pressure valve was somewhat open with lower pressure. This became a serious problem while running my final batch of sap for the season. Even with a new pre-filter cartridge the hose feeding the pump was much collapsed with much air. The pump made lots of noise, the motor became very hot and soon shut off from the temperature switch. It appeared the pump was being starved of sap. To troubleshoot, I ran the RO for a short time with the pre-filter cartridge removed. BINGO! Problem solved—good flow, no air, no noise.

I called Deer Run and explained the situation. They asked me the micron of the cartridge. It was 5 micron--what they had supplied me with and I had bought more. The man was very surprised: “We only run between 10 and 20 micron. Sorry you got 5 micron. I guess we had a wrong batch. It’s not letting enough sap through.” I also asked about gravity feed and he told me that some people add a small supply pump.

I was just about done anyway—peepers sang last night and the runs are over. But I’m wondering about you all out there with the same RO unit, or a similar unit.
Do you have similar supply issues? Have you added another pump? Do you use 5, 10, or 20 micron filter cartridges? Seems like 5 micron is the industry standard.
Will 10 or 20 gum up the membrane sooner?
What is your rinsing, washing, acid use like? I did fine doing a simple rinse and hot water circulation each night. How about year-end? Manual calls for storing membrane with RO water and rinsing every two months. Is that what you are doing? Do you know what make the membrane is? Can you use well water to rinse or wash? If not, can you create permeate for later washing by running well water through the unit?
How is your flow? This unit in effect has at least doubled my gph of water removal—almost 60 gph now combining the RO and the evaporator (one way of looking at it). Of course this changes as your brix rises. I’m happy with the output—6 to 8% sap into the evaporator is a huge time and wood saver. I just hope to solve the supply issue. Thanks for your thoughts.
Marc

[jrgagne99]

I would think the 10 micron filter would be ok for those membranes, especially if that is what he recommends. You might ask the folks at MES. I think that's what Ray uses. My Waterguys unit is similar to yours and I use a 20" 5-micron prefilter. I think it is a NF-270 membrane.

End of season I do rinse, wash, rinse, acid, rinse, wash, rinse. I think i go to 105 degF, IIRC. Then membrane preservative. This should work instead of having to run it every two months (pain). During season, I only rinse with 100 gallons of permeate each night. I use well water to do first rinse at beginning of year- 100 gallons.

The best thing I ever did to my RO was to add pump-less internal recirculation. This way you get you 6-8% in one "pass", but with multiple internal passes. With this, my single-post 4" supplies 7% at about 30 gph and 60 gph of permeate. Was a game changer because I can process sap right out of the truck while boiling at the same time. Don't need to run the RO ahead of time to build up enough concentrate first. Just set it and start boiling.

[maple flats]

On my Deer Run 250 I've used both 10 micron and 5 micron. In fact if I can get them I prefer 5 micron. Mine did when new come with 10 micron. Mine uses 2.5 x 20" pre-filters. One thing I've used for several years is a separate feed pump. For that I use a 1" 1HP electric booster pump, is has a SS pump head like this: https://www.northerntool.com/shop/to...2&gclsrc=3p.ds
I use it to feed the RO, even though a 250 has a feed pump, this improves the performance above original specs (about 10-15 GPH) somewhat. It puts about 70-75 PSI on the feed pressure gauge. That may fix it.
For storing, I leave the membranes in the RO, keep it from freezing. After a complete cleaning, Soap wash, rinse, acid wash, rinse I then add preservative. That stays in, I drain the wash tank.

[SeanD]

I have a Deer Run 250 that was just upgraded from the 125 expandable. It has its own feed pump that can handle the expansion. Running it as a 250 wasn't as easy as just flipping a switch and getting double the rate. Dave, here was a big help for me as a worked my way through multiple issues.

At the start of the season, my flow rates were ridiculously low - to the point I thought something was installed wrong. I called Ray and he said the new membrane needs a break-in period. I hadn't read anything about that here, but sure enough rates improved over the course of the season and I was eventually getting over 200 gph with 58-60% removal by the middle of the season.

In the second half of the season, flow rates were low because of the sap quality. My sugar content was still 2% or better, but the sap was very cloudy. My pre-filters are 10 micron. That's what Ray sends and what I've always used. I did have some issues there as well though. This is my first year recirculating sap back to a tank instead of running two separate passes, so I think that had something to do with my rising pressure and dropping rates. I would start the process 225-250 GPH and it would steadily drop to 150 GPH or even lower over an hour to an hour and a half. I inserted a piece of tubing inside the tank, so the sap would get drawn from about 12" off the bottom to see if that would help. I'm not sure if it did or not. I'll have to experiment with it more next year with better sap. I also think the recirculation is a factor because whenever I would stop recirculating and switch to my head tank, pressures and rates held steady every time from first boil to last.

Late in the season, the input/sap pressure would steadily drop as well. A brand new filter with fresh sap usually gives me 18-20 PSI. I had rates dropping below 5 PSI and the pre-filters were caving in - much like you shared about your hoses. As a 125 with separate passes a single filter would get me through both passes, the flush, and usually a wash and rinse. This year, I was changing filters before going to the head tank and before doing a flush/wash. For the final third of the season, I was going through 3 pre-filters per night.

I have a pump like Dave mentions here. Maybe I'll experiment with that next year to see if I can help push the sap into the RO. The filters caving in tell me the RO was starving for sap.

Ray now discourages the use of preservative. He says it eats the fittings and connections in the RO. He recommends flushing the RO with permeate 3-4 times in the off season. Fill your wash tank with the water. Recirculate it for 5-10 minutes and then go to the ground with it.

[Russell Lampron]

I would add a feed pump like the one that Dave posted a link to. I don't know if the 3/4 hp pump that you mentioned is supposed be a feed pump but if it is it's not doing it's job. I would remove that and just use the 1 hp pump in Dave's link. At 720 gpm it's more than adequate to supply your high pressure pump and that's a good price for a pump that size.

I would also swap out the 10" pre filter for a 20" pre filter and use 5 micron filters. You want to give your membranes as much protection as possible to help keep them clean so that they don't foul as fast and last longer.

[Mark-NH]

To start with the simplest-most obvious; you are starting each day with a fresh pre-filter, correct?

[maple marc]

Off season--been "off the air" for a long time. To review, I finished the 2021 season in March with 10 micron filters in my Deer Run Hobby RO. Yes, using a new filter at the start of each run. My supply problems were solved with the 10 micron filters. The hoses were not collapsing and the motor was not straining and getting hot. I've been following Ray's advice to simply rinse the membrane 3 or 4 times during the off season, not using any preservative. Today I did a rinse and noticed a sulfur "rotten egg" smell from the rinse water. Without using valve pressure, and all water coming out of the concentrate line, the smell eventually disappeared. I sampled a little water from the permeate line and got the same smell, so I closed the valve a bit to raise the pressure and run more water out of the permeate line. After some time I still had some smell. I'm hoping that at the start of the 2022 season when I do a full soap clean and acid wash that the smell will disappear. 2021 was the first season for this RO unit, so I would hate to think I ruined my membrane somehow.

[SeanD]

I've experienced that smell with some off-season and pre-season flushes. The soap wash will take care of it.