RO/DI system

[jeremy_rutman]

I'm used to getting various doodads from aliexpress (figuring most of what I buy locally comes from the same Chinese suppliers ultimately) and when planning my reef tank thought I'd give it a whirl for RO/DI.

I found inline filters:

• sediment (polypropylene media? )
• Carbon
• DI resin
• RO membrane filter

Would i need a flow restrictor after the membrane, and are these avail. with built in flow restrictors?
Does it seem like a reasonable setup? It sums to around 80$ . I dont particularly care about flow rates, I can leave this on overnight if need be.

 

[naterealbig]

They quality of the cartridges matter in this instance. What are the micron ratings of the carbon and sediment filters? (It does not say in the link, and also, the cartridges are not standard). What brand are they, and do you trust the name? Is the carbon filter a granular activated carbon filter, or is it a block? ( I see the link you provided states granular - which is sub standard, and has no chlorine/chloramine rating) What is the specific removal capacity of the carbon filter for chlorine and chloramine? What is the brand of the RO membrane, and do you trust it? (I noted the FROTEC brand name states 98% reject rate, which is good - if it's true. The hobby standard is Filmtec by Dow - and will list 5-10 years if cared for properly). Does it have a back flush system built in? If not, can you design/install one? Now that you've answered these questions, let's take a look at your water report. What is the chlorine and chloramine levels? Are the carbon blocks good enough to capture these levels? Any radioactive isotopes? If so, is the DI resin bed going to capture them? Don't forget, you will need a canister for the RO membrane, an inline TDS meter, and a mount to keep things together. I also saw that the DI is not color changing, so you don't know when it is exhausted. 4 out of five of the filters are not standardized, which means they will likely be more expensive to replace in the long run.

I'm not being ornery - but i am trying to make point . Your source water matters - and will be the very foundation of the ecosystem you are creating. If your source water is messed up, everything after that will be a battle. save yourself the head/heartache now, and cough up the extra $80 for a quality, trusted unit. Skimp on anything else but your RODI.

Spectrapure, Buckeye Hydro, and BRS al sell quality 4/5 stage units. My favorite, and personal recommendation is BRS 5 stage with universal carbon block. I'm sure others will chime in with their favorites.

BRS 5 Stage Reverse Osmosis Deionization Systems

Bulk Reef Supply - Saltwater Aquarium Supplies for Reef Tanks

www.bulkreefsupply.com

If your set on designing your own unit, we can help. I think you will find however, that after sourcing quality filters, there isn't that much savings in DIY in this specific instance.

 

[jeremy_rutman]

Ok thanks for the info . I'll see what the local guys charge for a BRS, as they don't ship to Israel.
If the local shops do the usual (namely, charge 3X the original price) then maybe I'll try sussing out a DIY again with your comments in mind.

I was advised from one of the local fish store guys who seems to know his stuff, that Mediterranean water (which is what I was originally planning on using, I'm 10min from the beach) isnt suitable for a reef tank. I could haul some Gulf of Aqaba water up every time I go to Eilat but its a ~5hr drive and I'm not sure how often I need to be changing the water. The corals down by Sharm El Sheikh are pretty amazing so the Eilat water is probably pretty good. When I was a kid growing up in Texas I set up a saltwater tank with Gulf of Mexico water that I set in a garbage bag in a closet for a couple weeks, on my dad's advice that that would kill off anything nasty in the water.

As an aside - is there any possibility of running a system that keeps itself clean enough that external water is only rarely required? I have seen some aquaponics systems that seem to be close in that sense; if I have a sump and do a lot of biologic filtering in a 150 liter system , is the water changing strictly necessary? How does nature deal ?

Some local water quality info I found : (BTW I don't think any physical method is going to be able to deal selectively with radioactive isotopes, that would require a mass-spec or gas centrifuge I blv which I have yet to run across in the local junkshops)

From here:

factor	MinimalRequired Residue, mg/l	Maximum Permitted Concentration, mg/l
Chlorine	0.1	0.5 / 0.8
Chloramines	0.3	3
Chlorine Dioxide	Not required	0.8

From here :


Required stabilization values include pH level of 7.5-8.3, dissolved calcium level of 80-120 mg/L as CaCO3, alkalinity of above 80 mg/L as CaCO3, Calcium Carbonate Precipitation Potential (CCPP) of 3-10 mg/L as CaCO3, and a positive Langelier Saturation Index.
A requirement of fluoridation at a concentration of 0.7 mg/L is planned to enter into force in 2017.
Main chemical contaminants were detected in drinking water sources in Israel: atrazine (in 8.4% of the sources, concentrations between 0.08-0.67 μg/L), simazine (in 13.4% of the sources, concentrations between 0.08-0.52 μg/L), trichloroethylene (in 13.7% of the sources, concentrations between 0.1-101.6 μg/L), and tetrachloroethylene (in 10.3% of the sources, concentrations between 0.1-176.8 μg/L).
In 2014-2016, 890 drinking water wells were tested for the presence of lead and only 16 (1.8%) had detectable lead concentrations (all less than 5 μg/L).
There are high concentrations of nitrates along the coastal aquifer.
Twenty-six percent of the drinking water has nitrate levels between 50-70 mg/L
An additional 17% had levels above the maximum permitted concentration in the drinking water standard (70 mg/L).

 

[jeremy_rutman]

Now that corona is mostly behind us locally I am back to thinking abt. my setup. I have access to an evaporator/condenser setup at my local makerspace - would it make sense to just boil water and condense it (maybe starting with sediment-filtered or bottled water) to get my 'RODI' water - and can I check the quality simply by measuring the electrical conductivity ?

 

[RocketEngineer]

You want to set it up so the filters before the RO membrane are enough to protect the membrane. Most times, a sediment then carbon block. Next, the RO membrane does the big cleaning 90-99% rejection so you have very little non-water still around. The DI beads get saturated very easily so you want them last, dealing with just the hardest to remove molecules.

The problem with distilled water is you may get metals dissolved in it you don’t want in the tank. Copper kills and several others are problematic. Drinking water normally has minerals added for taste and such which is also why it’s not ideal. RODI gets nearly everything out so you can then add only what your tank needs. Good luck.

 

[jeremy_rutman]

You want to set it up so the filters before the RO membrane are enough to protect the membrane. Most times, a sediment then carbon block. Next, the RO membrane does the big cleaning 90-99% rejection so you have very little non-water still around. The DI beads get saturated very easily so you want them last, dealing with just the hardest to remove molecules.

The problem with distilled water is you may get metals dissolved in it you don’t want in the tank. Copper kills and several others are problematic. Drinking water normally has minerals added for taste and such which is also why it’s not ideal. RODI gets nearly everything out so you can then add only what your tank needs. Good luck.

From what I've read on distillation it seems metals are removed (given their extremely high boiling points) but VOCs and other materials with boiling points lower than water will remain ; thus if I keep my input water at e.g 99C for an hour or so before distilling, allowing volatiles to boil out, then proceed to boiling+condensation, I'll have removed everything but those materials with a BP of between 99-100C, which as far as I know is only water.
The drawback for industry, namely energy use, is not such a biggie for me as I probably boil more water for coffee than I will for a 120L aquarium, I imagine.

 

[RocketEngineer]

What is the condenser made out of? That’s the big question. I’m guessing something metallic. If so, hot water will pick up ions off said surface. An RODI doesn’t carry that risk, that’s all. I’m not saying it can’t work in theory, I’m just going to stick with a system I can guarantee gives me pure H2O. Good luck.

 

[jeremy_rutman]

I can use a large Ehrlemeyer flask for instance, continuing with the laboratory glassware of the rest of the system. I don't think I'd have to worry about using a stainless steel vat either fwiw. Anyway I pay abt. 0.15USD / kWh for energy, and 1kWh gets me around 1kg or a liter of boiled water . It looks like I'd be paying around 300USD for a filter system, and 300USD of energy would get me about 2000L of water. If I replace 10% or 12L of my planned 120L system every week that's still more than 10 years before the filter system is cost effective.
Distilled water was the lab standard for pure water for years so I don;t think the purity is a sticking point. I am curious why others dont do this for small systems - I suppose some just buy distilled from the grocery store.

 

[Dr. Dendrostein]

I'm used to getting various doodads from aliexpress (figuring most of what I buy locally comes from the same Chinese suppliers ultimately) and when planning my reef tank thought I'd give it a whirl for RO/DI.

I found inline filters:

• sediment (polypropylene media? )
• Carbon
• DI resin
• RO membrane filter

Would i need a flow restrictor after the membrane, and are these avail. with built in flow restrictors?
Does it seem like a reasonable setup? It sums to around 80$ . I dont particularly care about flow rates, I can leave this on overnight if need be.

Save your money and get a no waste Ultra filtration RO system, add the DI resin like I did and you're ready. The amount of wasted water making filtered water you'll be buying a few reverse osmosis filters through your life. In other words, the waste of water is considerable. Especially if you go cheap

Again you need to add the D I resin to get 0 total dissolve salts.