Help Me Put Together an RO System

[Mr. Snook]

I've been looking at lots of pre-assembled RO and RODI systems and I think I'd rather fashion my own. For my needs, I'd like to be able to create about 1000 gpd (I have a very large aquarium - 700g or so). I don't need to worry about deionization because I plan to mix the RO with well water 2:1 to achieve the best parameters for my cichlids.

Here is the setup I was planning... Well water would come in to a 20" x 2.5" canister with a sediment filter in it. Next it would go through another 20" x 2.5" canister with a carbon block. Then a booster pump to push it through two 500 gpd membranes in series. I may add one more carbon block after that.

Any recommendations for a booster pump on this set up? My well water comes in at 40 psi, which is pretty low. All input and suggestions welcomed.

 

[TwoTankAmin]

I run an RO/DI unit but at much smaller volume than your need. My system is 3 modules - carbon> RO> DI. I mix it with my well water. I do not understand why you think you do not want a DI module because you have well water? I can tell you that my tds meter basically reads 0 for my output water. I am using my unit for a tank with Altum angels. My tap is pH 7.0 and the TDS are 83 ppm. My tank water is pH 6.0 and TDS at about 60 ppm. My mix is 11:9 (RO/DI:Tap).


Now I need only 11 gallons/week of RO/DI, but I batch and store it. However, if you want to change water weekly and you change 50%, that means about 325 gals (your tank does not hold 700 gals of water, it would be more like 650 or so). It is not filled to the absolute top and it contains substrate and decor which also displace volume.

I see no need for 1,000 gpd if you can store it. Have a look here https://jehmco.com/html/water_storage_tanks.html There are even "slim" style tanks where space is a consideration. (Special large capacity narrow sizes to fit through doorways or behind racks of tanks.) Jehmco sells all sorts of pumps. They basically sell supplies for folks with fish rooms. While my largest tanks is only 150 gal. I have 20 tanks in all and I shop there for central air and frozen foods. John, the owner, is very helpful in coming up with solutions. He should be able to help with a pump.

Slim Storage tank
375 gal. 30" L x 62"W X 60:H 16" DIAM. Fill Opening 1.25" Bulkhead drain

Horizontal Cylindrical tank with molded in legs.
325 gal. 38" Diam. and 49"L 2" Bulkhead drain


I saw a "High Output Tankless RO On Demand Reverse Osmosis System." This is designed for home drinking water oR small commercial operations, but there is no reason it wont work for an aquarium or that one cannot store the output water.

Continuous flow system outputs a continuous flow up to 1/2 gallon per minute.
High efficiency - recovery rate up to 29%
Standard RO systems operate at 20% recovery, with lower recovery rates common as the tank fills. With no tank the PRF-RO offers significantly reduced waste.
No pump required
Will deliver as much as 1/4 gallon per minute with standard line pressure of > 40 psi.
No tank - on demand system
System makes water when you need it, so there is no tank required and no worries about running out of treated water.

If you can store water this makes 15 gph or 360 gpd at 40 psi input. This is from the same place as I got two 75 gpd portable RO/DI units. My brother uses one to mix water for use in humidifiers.
https://store.afwfilters.com/revers...tankless-ro-on-demand-reverse-osmosis-system/

 

[Mr. Snook]

Well, here’s my thinking on the DI… I don’t need my TDS to be as low as yours, so I don’t need absolute zero as a starting point. If you’re going to be mixing well water back in with that 0 TDS RODI, you’re adding back stuff that the DI would have removed, so simply adjust the ratio accordingly to produce an acceptable TDS level. DI resins are very expensive and deplete quickly. I’d like to eliminate that expense if possible.

My estimation of total water volume is based on what the tank and sump (combined) hold. Sure, I could be off by a bit – this was just a guestimate. I’ll be storing the water in two 300g reservoirs, one of which will be emptied each week into the tank for water change. From our well we get only about 40 psi, so the booster pump would be necessary to get it up to around 80 psi. That on-demand system is interesting and would eliminate the need for a pump, but my preference would be to get that storage tank filled up after the water change. I can add 100g of well water and then top it off with RO and have it filled in about 5 hours (more or less) with a 1000 gpd system. I like this a lot better than leaving it to fill over several days. But that’s just me!

Good call on reaching out to John at Jehmco – I’ll drop him a line today re the booster pump.