Tabletop RO systems?
 

I live in a rental with metal pipes and didn't feel comfortable messing too much with them to install an RO system. When considering options I realized that I could snuggly fit a tabletop RO system between the toilet and the bathtub, by installing a diverter in the toilet's cold water supply I could activate the RO system that way and simply fill up my jugs when needed and let the waste water go in the bathtub.

My other options would be to use the Washer machine's cold water supply, also using a diverter to send the water to either the RO System or the washer. This is located in the bathroom and the waste water could be flushed into the bathtub as well.

However, I'm not sure if a tabletop RO system would suffice living in Los Angeles, with a chlorinated water supply and pretty hard water. A tabletop system such as this Amazon.com has five stages. My guess is that the filters are smaller than the under the sink RO systems we're used to see (like this one Amazon.com) so they would need more frequent replacing.

But other than that, would a countertop RO system get the job done?

Check out the different systems that Ray offers for sale.

Mateo.

The CTRO (Counter-Top RO) that I offer is quite similar to the one you linked at Amazon, but 1) without the DI cartridge (which I recommend against), and I use a 50 gpd LOW-PRESSURE membrane, while theirs is a 75 gpd standard-pressure one. I also supply 2 years' worth of replacement filters with it for the same price.

Their membrane will likely extract 98% of the dissolved solids versus the 93% of the LP membrane, but that may-or may not be an issue.

Standard membranes are rated at 65 psi & 77° water at the membrane. The LP membrane is rated at 25 psi and the same temperature, both of which affect the output.

Let's assume you have 45 psi water pressure at the membrane (and the temp @ 77°). The 75 gpd membrane will have a capacity of 69%, or around 51 gallons/day. The LP membrane, by contrast, would put out about 30% more, or 65 gpd.

FWIW, I have sold over 100 of those over the last decade (I use one myself).

Ray's unit sounds like exactly what is needed. The output may be 10-20 ppm (not zero) and that's fine. I would also not worry about low-ppm of chlorine (or actually likely chloramine) in the water. That might be an issue with fish, but not orchids. That Amazon unit with 5 stages sounds like total overkill. You don't need all that stuff.

Timely information since I am thinking about a system and would be looking for a tabletop unit. Questions I have is, do you need to adjust the PH and use Calcium and Magnesium when using an RO System?

Don't worry about pH. Use a fertilizer that has calcium and magnesium (like the MSU pure water formula, or K-lite). Problem solved.

Based on your responses I think it's fair to assume that 3 stages is fine for an at-home RO system. And seems like many of you have positive experiences with countertop ones.

The under-sink ones usually add two carbon filters, my understanding is this is to reduce chloride, but sounds like a bit of chlorination won't be too relevant for the orchids. But would it render products like Quantum or Inocucor ineffective?

Back in the day, the material used to make membranes were easily degraded by chlorine. The carbon filters were a way to protect the membrane, but that is far less important than it once was, courtesy of newer engineering materials.

In a standard 4-stage residential RO system, the water flow is through:

1. sediment filter
2. carbon filter
3. membrane, and
4. carbon post filter, added to capture any residual organics or tastes from the membrane.

A 5-stage system adds a second carbon cartridge before the membrane. The post filter is unnecessary for plants.

Certainly, chlorine is bad for microbes; that’s why it’s added to water. However, it is rarely outside of the 1-4 ppm range and a carbon filter and the membrane itself pretty much eliminate that.

I got some choramine/chlorine test strips to see what, if anything, I was dealing with. The tap water supply is barely at the detection limit of the strips (1 ppm) So of course there isn't any on the output side. My RO unit is 3 stage (sediment filter, carbon filter, membrane). My under-sink unit is the same. Maybe the extra carbon filter is needed in some localities with higher chlorine or chloramine levels.

You very likely can find those test strips at an aquarium-supply store. If not, certainly from Amazon (which is I think where I got mine). But before you rush to treat a problem, see if you have one to begin with. My suspicion is that you don't.

Thank you everything in this post was very helpful.