DIY passive RO generator

[CWO4GUNNER]

After some experimentation I can now confirm that use of painters clear thick Visqueen $5 for about 50 SF, is effective in drastically reducing evaporation in dry climates, Saves on chilling and heating cost, and generates for me about 1/2 gallon of purified water (PW) daily per 4 square feet of tank surface area and for me that comes out to about 10 gallons of RO per-day without the use of power or equipment. This method PW generator has been around for a bout 100 years

Example below visqueen is cut to size with about 4 inches of overhang and laid over the tank with all covers and lighting removed, the back-splash portion is left pointing up to allow air and access. Note how initially the plastic drapes onto the water, this will change.


Below the glass lids (on top of visqueen) and lighting (on top of glass) are placed back on and the visqueen slack is pulled tight enough so that only the middle portion touches the water providing a path for PW condensation flow back to tank. Visqueen is held in place by glass lids.


Below you can see how most of the visqueen is out of the water collecting and condensing evaporating water which collects and under gravity forced to return to tank purified. Purified water which is better then RO of course.

My tanks are now at about 98% natural cycling and self purifying to the point where most waterchange maintenance is now almost redundant in my highly specialized setup.

 

[tolawdjk]

Correct me if I am wrong here, but this doesn't add "new" RO to the tank, but just reduces and captures what would have been normal evaporative losses and returns it to the tank. If you had high TDS prior to this, you are still going to have high TDS after, you just will be decreasing the rate of increase do to evaporative losses.

 

[CWO4GUNNER]

Correct me if I am wrong here, but this doesn't add "new" RO to the tank, but just reduces and captures what would have been normal evaporative losses and returns it to the tank. If you had high TDS prior to this, you are still going to have high TDS after, you just will be decreasing the rate of increase do to evaporative losses.

Well lets see.. considering the initial investment of an RO system with booster pump, annual power usage, not to mention the generation of brine waste water. All that stuff and $$ verses my initial investment in $5 of visqueen, the application of physics, and no recurring cost or waste...Hmmmm. Yup your your right although it would cost you dearly, your system far more complicated, and RO not as pure as purified which just about evens up the TDS comparison, yes would definitely have me beat by about 4% in water generation output.

 

[tolawdjk]

I was just attempting to understand what your pictures are describing, I'm not attacking what you have done in anyway. I didn't discuss RO investment, pumps, power usage or jack squat about water generation output.

As I understand it, the visqueen seals the tank, minus a few small openings allowing air to enter. The tank water evaporates, condenses on the visqueen, flows by gravity back into your tank.

Now, if your initial tank fill had 20 ppm hardness, that ion mass is staying in the tank. The evaporative water is purified, yes, but the tank water contains the same initial ion mass. That is, unless you have some method of removal that I'm not understanding in how you have described it.

Now, if added a seperate collection vessel to collect the purified water, and then added that to your tank, I could see that being beneficial in improving water quality. Especially if I had a large tub/tank unused that could be set outside and sealed up to collect pure water.

 

[Khemul]

I'm wondering the same thing as tolawdjk. As I always understood these systems, they work by seperating the water from a dirty source into a different container. Otherwise you'd just be dropping the pure water back into the tank (which is the dirty source in this case).


Maybe we are missing something. I do like the idea of coming up with odd ways to do things that cost way more then they are worth also. :laugh: Just don't see how this is purifying the water if the purified water is being dropped right back into its source.

 

[knifegill]

Before claiming victory, you need to test your TDS to see how ineffective your setup is. While your nitrates may be low, and the little puddles of water are basically distilled, the main tank's water is only becoming saturated with waste. Removing water and adding it back to the tank in purefied form is like squeezing out a sponge and then laying the sponge in the puddle you made. You're not actually diluting your tank at all. Just temporarily letting part of the water leave and return. No benefit.

 

[Rbishop]

LOL..glad it is working for now! I think the whole theory is bit out the window.

 

[Khemul]

...While your nitrates may be low....

Pretty sure it is only the TDS that'll be effected. The nitrates are taken care of by the Pothos tree growing out of the filter. :laugh:

At worst it seems like a good first step towards a DIY system. I mean maybe it could be adapted to seperate out the pure water and give something back for water changes.

 

[e5anderm]

It's a decent first step towards a very basic DIY RO system but its still flawed right now, not sure how to make it better at the moment, but I will add this.

Stand alone home RO systems use several types of filtration, first to take out the large particles, then the medium and eventually they use a very fine RO membrane to take out the smallest particles they can. Very few are truly 100% efficient, but most are 95%+ efficient and are very good at lowering down TDS from say 150-200 to around 1-10 or so particles. However, these systems are set up in a way that the particles that are removed are stored and eventually cleaned up (by the person) so that only the pure water actually exits the system into a RO holding tank.

With your design, it seems you don't have a way to stop the TDS particles from ending up back in the tank, the idea of a membrane to purify the water is good but your design could use some work so that the TDS particles (redundant, I know) are not allowed back into your tank. Either that or none of us fully understand your design.

 

[CWO4GUNNER]

Anyway for those that get it! For those that have a need to drastically lower evaporation affects on water. For those that see the wisdom in avoiding the expense of an expensive automatic RO replenishment system, this is your answer. A very simple to understand and effective solution that works for all the reasons I mentioned. Im so confident it works Im even reaching above the nay-fray to let you know how well this works...:clap: