3/8” RODI

[second_decimal]

So I have a long run (@50ft) from my RO unit feed line to the main unit (very old 7 stage 90gpd spectrapure max cap) and then the return and exhaust are also just about as long. I am using an aqua booster pump (boosted to @80psi) and with that set up, was getting zero effluent.

I now replaced feed line with 3/8” directly to the booster pump and then kept on going with stage 1 and stage 2 where output goes back to 1/4” JG fittings for stage 3 and the rest. When the booster pump kicks on now, it boosts to 100psi and I am getting 0 tds effluent.

I am getting ready to upgrade the rest of the plumbing to 3/8” connections just because the volume increase (despite 1/4” connection bottlenecks) but am wondering about volume and filter effectiveness that may be affected. Could anyone with some experience give me some feedback on why or why not 3/8” tubing? Do I need a bigger Membrane like 500gpd or whatever?

Thanks

 

[DenverSaltyFarm]

how big is your aquarium and how big is your storage tank?

 

[second_decimal]

What role would that play in the equation?

 

[DenverSaltyFarm]

What role would that play in the equation?

well you mention if you should use a 500gpd system, if you have say a 90 gallon aquarium and you want to get a 500gpd RO system then you would be complete overkill. if you have a 2000 gallon aquarium and a 500 gallon holding tank then a 500gpd RO is normal for a system like that.

just seeing the size of your tank also what your house water pressure is to start with without the booster pump so I can easily answer your questions.

 

[second_decimal]

I have a IM25Lagoon and (2) 150g storage tanks

 

[second_decimal]

House psi at the unit was around 40psi. After upgrading feed line it jumped to 60psi. The booster pump added 20psi for both.

 

[second_decimal]

But seriously, as previously mentioned, rather than an application question, it is more of a technical question. My apologies, I should have been more clear.

My concern was that the increased flow rate would overwhelm the membrane despite the membrane housing, as well as stage 3 housing entry and exit, being necked down to 1/4” entry and exit(s).

Is it necessary to add a secondary membrane, a membrane rated at a higher flow rate or should I stick with a normal 90 gpd? Can I verify/monitor with tds meters?

Really, the challenge here is to overcome the long feed, effluent and waste line distances. The unit, with 3/8” line to the unit and up to stage 2 exit @ 60 psi, is producing about 76 gpd on a 90gpd membrane. With 1/4” That actually sufficient for me. I was just hoping maybe someone had played with this type of upgrading before and what the experience was.

 

[disaster999]

Can you draw a simple diagram or even take a picture of your setup. The way how you described it and the terms you are using is giving me a headache. Why are you having the RO unit sit 50ft away from the rest of your filter? You mentioned RO unit feed line to the main unit, return and exhaust all have a 50ft run, then threw in effluent in the mix in the next sentence. You know that, by definition, effluent = waste water right? You go and say have zero effluent (liquid waste by definition) with 1/4" then goes and say effluent (waste water) have TDS of zero with 3/8"???? Just use SIMPLE terms if you dont understand the lingo. Theres water supplying/feeding the RO filter, filter RO water exiting the filter, and waste water from the RO.

Also what is it that you are trying to achieve here? Are you trying to increase your production? increase your efficiencies? Producing 76 gals is sufficient for you...so why are you upgrading then? Nothing you mentioned makes any sense. You say you have a 25 gal AIO but have TWO 150G STORAGE TANKS? are you trying to make 2 years and 4 months worth of RO water for water changes in one go?

 

[disaster999]

The flow through the RO membrane all depends on the size of the flow restrictor and you should choose the right one for the membrane you have. You can monitor the efficiency if the increased flow by checking the TDS going in and out of the RO membrane and checking the rejection percentage. The increased pressure and flow will have no effect on the housing or other membranes, they are designed to handing a lot more. Ive pumped over 150psi through my no brand chinese housing and its fine.

 

[second_decimal]

Oof, sorry it’s giving you a headache. I did mistakenly use the term “effluent” instead of “permeate” so I can understand the confusion. It was late and I simply confused the term as it happens occasionally to me these days.

Pretty simple to switch the two and make sense of what you’re looking at though.

can you tell me who in their right mind would need 2 150g storage tanks for a 25g aquarium? Me neither… as I mentioned before, the application shouldn’t matter and it’s really not a concern to me how big the tank and how fast I'm trying to fill it.

Im really more interested in why RO units come outfitted as 1/4” and if anyone has taken the time to upgrade to 3/h8” tubing what challenges they encountered and what benefit they received. I’m ok with 76 gpd because it meets my current needs but that doesn’t answer any of my questions.

I put it out there in the hope someone had done this and could give some feedback.

 

[disaster999]

i mean, when 1/4" is sufficient, why bother with more expensive 3/8" tubing and fittings, not to mention the extra space it takes up, and the bigger bending radius required for the larger lines, just for marginal, or in normal application (without traveling 150ft of 1/4" tubing), no significant gains at all.

Also, The context totally matters. We base our advise on your specific application. Who knew you just want to know the answer to a what if question.

 

[second_decimal]

Thank you for the information. I did see auto shut off units with 3/8 fittings and 3/8 y connectors for a flush kit. Found flow restrictors but didn’t know what flow rate I need. The smallest membrane housing with 3/8 size fittings is as 500 gpd. I don’t need that much but I need the membrane to function properly so was wondering if I would need that as well.

While 76 gpd is ok right now, I would just be chasing faster fill times (and the fun of redoing my ro).

 

[second_decimal]

1/4” was initially insufficient because the hose where all so long. I was getting no… permeate That’s what drove the project to upgrade. That went well and now I’m producing 76 gpd. Now I’m thinking of upgrading whatever connections I can to see if can find additional gains

 

[Sisterlimonpot]

The way that an rodi works, I don't see any benefit what so ever to increasing the connections to a 3/8" tube.

I don't think flow restriction is an issue with rodi units, in fact flow restriction is one of the main ways to create the right amount of rejection and efficiency.

If for some reason you achieved results by simply changing out one tube with a larger diameter would be dismissed as coincidence and boosting the pressure was probably what yielded a positive result.

I don't know what your maintenance routines are, however if you allow the carbon blocks to become spent, then you're also degrading the effectiveness of your membrane to the point that it will definitely clog.

Normally a complete overhaul of the prefilters and membrane might be in order to get your unit back up and running.

All in all, retrofitting your unit with 3/8" hose wont do much of anything for you.

 

[Sisterlimonpot]

So I have a long run (@50ft) from my RO unit feed line to the main unit

Are there any kinks in the waste and/or effluent line?

 

[second_decimal]

Good thought. It’s a straight run, no kinks.

 

[disaster999]

Going back to your setup, why is your RO membrane located 50ft away and need another 50 ft (is it going back to the main unit??) for the filtered RO and waste water? Theoretically, 1/4" with sufficient pressure should still be able to push through the tubing going that far. If you arent getting any flow with 1/4", it wouldnt magically just work with upgrading to 3/8". Are you sure there arent any blockages in your 1/4" lines?

 

[Daz_1978]

Are you sure there arent any blockages in your 1/4" lines?

There was one, until he increased the pressure to 100psi.



In short: Yes! 3/8" lines will give you more flow at the end of the line. It's less restricted.

I had to read a lot to get here, so I might be fuzzy on some of the details. I believe you wanted ideally 90psi, but ended up with 100psi via pumps and tubing upgrades, right? I think 90psi is a tad high, but don't know the specs of your unit. I'd certainly check the pressure rating of the unit, fittings, and tubing.
Throw a pressure regulator on the input tube, restrict it to 90psi.

Do your upgrade! Have fun!

 

[Buckeye Hydro]

I'm with the commenter above... this thread gives me a headache!

For feedwater runs longer than about 15 to 20 feet, yes, it's a good idea to move up to 3/8" tube.

Also remember that the ideal location for your booster pump is AFTER your prefilters.