DIY high output Reverse Osmosis unit

[illumnae]

I'm trying to set up a large daily auto water change system for my 600 gallon tank and due to the lack of options locally for high output reverse osmosis systems (I'm not located in the United States) am looking to assemble my own. I'm using this diagram as the foundation of my build:

I am thinking of having a dual membrane 400gpd system for a total of 800gpd, but due to limitation of parts may end up doing a dual membrane 200gpd or single membrane 400gpd system instead. However before I do this, I have some questions.

1. The largest flow restrictor available to me locally is 1500cc. Based on some research I did, an 800cc flow restrictor is only good enough for a 100gpd system. To get around this problem, can I split the waste line into 4 lines, each with a 1500cc flow restrictor so that there is a total of 6000cc? If I go with a 400gpd system then I would just split it into 2 lines, each with a 1500cc flow restrictor for a total of 3000cc. Can I combine the lines back after the flow restrictors to form a single drain line? It would look something like this:

2. I would also like to install a booster pump, but am unable to find one available that is rated for 800gpd. Is there a way I can get around this by installing 2 booster pumps in parallel or am I limited to 400gpd?

3. The booster pump I am looking at states in the specification that inlet pressure is 30psi, operating pressure is 80psi and pressure bypass is 140psi. Does this mean that the booster pump automatically switches off when the rodi barrel is full and the float switch is up and psi exceeds 140psi, or do I still need to install a separate pressure switch? For reference here is the spec sheet:

Thank you very much for your help!

 

[SlugSnorter]

Bump

Also, it could be better to setup a system with a lower GPD and have a storage tank that it fills and uses plus it could mix and heat within the storage tank.

 

[illumnae]

Bump

Also, it could be better to setup a system with a lower GPD and have a storage tank that it fills and uses plus it could mix and heat within the storage tank.

The single membrane 400gpd unit would be my backup plan, but I need help on my questions above so I can proceed to assemble it!

 

[a.t.t.r]

How many gallons are you changing in a day!?
I ran a whole fish store on three 100gpd membranes and that included water we sold to people as well.

also when membranes are in series you only need a restrictor rated as if there was only a single membrane.

 

[SlugSnorter]

The single membrane 400gpd unit would be my backup plan, but I need help on my questions above so I can proceed to assemble it!

How much GPD do you want? you really dont need more than 100gpd for a daily 10% change in your tank


dchild=1&keywords=Best+Reverse+Osmosis+System&qid=1632848892&sr=8-11

random thing on US amazon, what region are you in? They probably sell there too.

 

[illumnae]

How many gallons are you changing in a day!?
I ran a whole fish store on three 100gpd membranes and that included water we sold to people as well.

also when membranes are in series you only need a restrictor rated as if there was only a single membrane.

I would like to assemble a much larger unit to take into account the other tanks in my fish room in addition to the 600 gallon. Also, the current 200gpd unit I'm using generates much less than 200 gallons per day so I think it's better to oversize.

Thanks for the information on the flow restrictor! So for either the dual or single membrane setup, can I do a split in the waste line and use 2 of the 1500cc flow restrictors since I am not able to obtain a single 3200cc restrictor?

How much GPD do you want? you really dont need more than 100gpd for a daily 10% change in your tank


dchild=1&keywords=Best+Reverse+Osmosis+System&qid=1632848892&sr=8-11

random thing on amazon, what region are you in?

I would like a larger system to take into account my other tanks as well. I have other tanks that are freshwater that I use ro water to do large water changes too. Please just assume I need the large system whatever the reason, and I would greatly appreciate assistance on the questions I have, thank you!

I am located in Singapore

 

[a.t.t.r]

I would like to assemble a much larger unit to take into account the other tanks in my fish room in addition to the 600 gallon. Also, the current 200gpd unit I'm using generates much less than 200 gallons per day so I think it's better to oversize.

Thanks for the information on the flow restrictor! So for either the dual or single membrane setup, can I do a split in the waste line and use 2 of the 1500cc flow restrictors since I am not able to obtain a single 3200cc restrictor?

I would like a larger system to take into account my other tanks as well. I have other tanks that are freshwater that I use ro water to do large water changes too. Please just assume I need the large system whatever the reason, and I would greatly appreciate assistance on the questions I have, thank you!

I am located in Singapore

You should be fine splitting it into two destructors. It may not be exact due to pressure drop but will be close enough.

 

[elysics]

Putting the membranes in series is to get a better wastewater ratio (while sacrificing price point and having dirtier output) not really to get higher output. For high output you could put them in parallel, basically run 2 ro systems side by side after the filters.

Or if at all possible, look into sidestream membranes, they do both high output and a 1:1 output to wastewater ratio more or less.

 

[WVNed]

I would like to assemble a much larger unit to take into account the other tanks in my fish room in addition to the 600 gallon. Also, the current 200gpd unit I'm using generates much less than 200 gallons per day so I think it's better to oversize.

Thanks for the information on the flow restrictor! So for either the dual or single membrane setup, can I do a split in the waste line and use 2 of the 1500cc flow restrictors since I am not able to obtain a single 3200cc restrictor?

I would like a larger system to take into account my other tanks as well. I have other tanks that are freshwater that I use ro water to do large water changes too. Please just assume I need the large system whatever the reason, and I would greatly appreciate assistance on the questions I have, thank you!

I am located in Singapore

I don't think it works that way. The flow restrictor creates backpressure in the waste line which generates pressure in the RO membrane housing to force water through the membrane which comes out the product line.
I think if you put 2 in parallel like that you would get half the flow and not twice the flow you are expecting. You want to make this.
https://www.buckeyehydro.com/the-gapper-light-commercial-ro-system/


@Buckeye Hydro

 

[SlugSnorter]

I would like to assemble a much larger unit to take into account the other tanks in my fish room in addition to the 600 gallon. Also, the current 200gpd unit I'm using generates much less than 200 gallons per day so I think it's better to oversize.

Thanks for the information on the flow restrictor! So for either the dual or single membrane setup, can I do a split in the waste line and use 2 of the 1500cc flow restrictors since I am not able to obtain a single 3200cc restrictor?

I would like a larger system to take into account my other tanks as well. I have other tanks that are freshwater that I use ro water to do large water changes too. Please just assume I need the large system whatever the reason, and I would greatly appreciate assistance on the questions I have, thank you!

I am located in Singapore

I think it could be easier to potentially have a few smaller systems

 

[a.t.t.r]

Putting the membranes in series is to get a better wastewater ratio (while sacrificing price point and having dirtier output) not really to get higher output. For high output you could put them in parallel, basically run 2 ro systems side by side after the filters.

Or if at all possible, look into sidestream membranes, they do both high output and a 1:1 output to wastewater ratio more or less.

the better waste water ratio is by having having more output.

You do them in series the tds rise by having a second membrane is minimal.
When I did the LfS I was running 3 in series. You could also run in parallel and go to a single restrictor. (T on the waste output combining likes) however simpler to just run in series and not worry about it.
Don’t waste water.

 

[elysics]

the better waste water ratio is by having having more output.

You do them in series the tds rise by having a second membrane is minimal.
When I did the LfS I was running 3 in series. You could also run in parallel and go to a single restrictor. (T on the waste output combining likes) however simpler to just run in series and not worry about it.
Don’t waste water.

Just meant to say that two in parallel will give you even more output than two in series, which will still give a bit more than just one membrane. But you are right, singapore probably isn't high up on the list of places with abundant water.

 

[a.t.t.r]

Just meant to say that two in parallel will give you even more output than two in series, which will still give a bit more than just one membrane. But you are right, singapore probably isn't high up on the list of places with abundant water.

Two in series vs parallel should have virtually 0 impact on clean output. I series we are talking. Waste of first time input of second and the restrictor is on the second one.

 

[illumnae]

Very sorry but I'm starting to get lost in the discussion.

I understand running 2 in parallel means splitting the source water into 2 separate membranes which would also split the input pressure and require separate booster pumps for each membrane.

However when we talk about running 2 in series, are we referring to the waste line of the first membrane going into the input line of the second membrane like a typical dual membrane system, or the clean water line of one membrane going into the input of the second? The former makes sense but the latter doesn't

 

[illumnae]

You should be fine splitting it into two destructors. It may not be exact due to pressure drop but will be close enough.

I don't think it works that way. The flow restrictor creates backpressure in the waste line which generates pressure in the RO membrane housing to force water through the membrane which comes out the product line.
I think if you put 2 in parallel like that you would get half the flow and not twice the flow you are expecting. You want to make this.
https://www.buckeyehydro.com/the-gapper-light-commercial-ro-system/


@Buckeye Hydro

Wouldn't each 1500cc flow restrictor in a split line create its own back pressure which would then combine upstream to greater back pressure in the main line? This is what @a.t.t.r posted above too. It wouldn't be the equivalent of a single 3000cc flow restrictor but it should be close? I don't understand why it would be half (750cc)

 

[WVNed]

Wouldn't each 1500cc flow restrictor in a split line create its own back pressure which would then combine upstream to greater back pressure in the main line? This is what @a.t.t.r posted above too. It wouldn't be the equivalent of a single 3000cc flow restrictor but it should be close? I don't understand why it would be half (750cc)

A flow restrictor doesn't create pressure. It holds back the pressure from the source water line or created buy a booster pump. That pressure had one hole to escape through. If you give it 2 holes to escape through do you think the pressure now held back will be more or less than with one. I think it would be about half.

 

[a.t.t.r]

A flow restrictor doesn't create pressure. It holds back the pressure from the source water line or created buy a booster pump. That pressure had one hole to escape through. If you give it 2 holes to escape through do you think the pressure now held back will be more or less than with one. I think it would be about half.

Pressure won’t drop (by much)until it exceeds the inlet flow rate. Restrictor are rated by how much let let pass. If you need 3000ml and only have 2 1500 runnin them parallel will be apx same along with the same apx pressure drop you would have had with a single 3000.

And yes we are talking about running the waste of one into the inlet of the other and the restrictor goes out the waste of the second unit.

 

[outhouse]

Two in series vs parallel should have virtually 0 impact on clean output.

Actually it does. Incoming TDS dictates whether to run series or parallel

 

[outhouse]

I understand running 2 in parallel means splitting the source water into 2 separate membranes which would also split the input pressure and require separate booster pumps for each membrane.

You should not need a separate booster. You only use this configuration if your incoming TDS is to high. When TDS is high incoming you dont want to run in series because your product coming out of second membrane will be to high. IN parallel the DI resin will last longer

However when we talk about running 2 in series, are we referring to the waste line of the first membrane going into the input line of the second membrane like a typical dual membrane system

Yes exactly. If TDS is low then this is how you want to run. I use 3 membranes and make 300 GPD

or the clean water line of one membrane going into the input of the second?

NEVER do this. unless TDS is off the charts high and water is free. it will waste water.

SO last thing that needs to ne NOTED here. As far as restrictors go, it all depends on your incoming TDS, and you can tune how much restriction is used, this will maximize output verses waste water. My point you can play with different amounts. in parallel 500 to 1000 possible with 800 being common. In series if incoming TDS is low you can decrease waste water flow.

 

[Mike konesky]

3 pairs of 100gpd membranes. 3 boosters. 3-800 restrictors. There's your 800gpd. The 100gpd membranes CAN be 99% rejection which would save more money. I have no experience with the larger membranes so can't help there.