RODI Controller

Projects General Guidance
1

Hey guys and gals :slight_smile:

I'm at it again...
Trying to build an Automated Reverse Osmosis controller.
This "device" would log filter minders and replacement dates, water usage and production, Automatic Flushing and multiple TDS readings.

Inputs :
3x Flow Sensors - 5V Hall Effect Type ( In / Waste / Clean Out )
6x TDS probes ( Input / Pre-Membrane / Post1 / Post 2 / DI / Spare )
4 x Pressure sensors ( Main / Pre-Membrane / Water Storage Tank / Spare )

Output :
6x Solenoids ( Flush / PF / P1 / P2 / RO / DI ) - 24V 4.8W each
1x Booster Pump Control

Other Modules :
RTC
EEPROM

Plan is to build a shield that would allow easy hook up in case others might want in on this.
Using an external Relay board would allow 5V control of relays and opto isolation. This would mean being able to run an single 24V power supply and an DC / DC inverter for the 5V required by the Arduino and other sensors

Now the question is...
Which board would be best suited for this specially if IOT is on the "things to add" list ?

2

Parts List :

As you can see, my approach is a modular one and rather an inexpensive one...

3

Adrculda:
Hey guys and gals :slight_smile:

I'm at it again...
Trying to build an Automated Reverse Osmosis controller.
This "device" would log filter minders and replacement dates, water usage and production, Automatic Flushing and multiple TDS readings.

Inputs :
3x Flow Sensors - 5V Hall Effect Type ( In / Waste / Clean Out )
6x TDS probes ( Input / Pre-Membrane / Post1 / Post 2 / DI / Spare )
4 x Pressure sensors ( Main / Pre-Membrane / Water Storage Tank / Spare )

Output :
6x Solenoids ( Flush / PF / P1 / P2 / RO / DI ) - 24V 4.8W each
1x Booster Pump Control

Other Modules :
RTC
EEPROM

Plan is to build a shield that would allow easy hook up in case others might want in on this.
Using an external Relay board would allow 5V control of relays and opto isolation. This would mean being able to run an single 24V power supply and an DC / DC inverter for the 5V required by the Arduino and other sensors

Now the question is...
Which board would be best suited for this specially if IOT is on the "things to add" list ?

A few observations.
Manufacturers say thing like filter is good for 3000 gallons or 6 months whichever is soonest.
Mostly it's complete B*****S designed to part you from your money.
Pressure drop across a filter will tell you if it needs changing.
Flow rate is a good indicator of something wrong.

Hugely dependant on the supply though.
For a municipal supply the water quality is fairly constant.
The first filter should have a clear housing so that a visual inspection can see when it gets mucky.
Watch out for the carbon filter though, although municipal supplies have fairly constant chlorine content, its very difficult to know when the carbon filter is exhausted as chlorine ion detectors are very expensive.
There are one off manual test methods though.
My domestic unit has had the same carbon filter for 15 years or so with no problem.

Back flushing can be done with purely a volume measurement as if there is a sediment build up the pre filters will become clogged before it becomes a problem. (IME).
I used to use rainwater as a feedstock , that really needs a sediment tank if you do not wish to be changing pre filters regularly.

Adrculda:
Now the question is...
Which board would be best suited for this specially if IOT is on the "things to add" list ?

I suggest that depends on your sensors.
My current TDS project would require three digital pins per sensor.
Although it only needs one component, a capacior.

EDIT

Booster pump control, these are normally simple pressure switches , and i do not see any benefit to automating this in any way except perhaps if you have a large variation in supply pressure.

4

Thanks for your input.

My main indicator would be the the amount of clean water it has produced measured by the flow meters, In ( Total ), Clean VS Waste and then comparing the TDS readings to flush accordingly when efficiency deviates from the norm. My city water at the moment "floats" around 150-170ish PPM and around 75psi which changes through out the day as water is being used.

My RO setup is a BRS 5+ system and all the filters have a clear housings.
I'm adding a second 100GPD membrane to upgrade to a water saver model and reduce waste but I would have to add in another flow sensor to monitor the amount of clean product it makes.

The pressure sensors will be placed at the Main, after sediment and after the carbon stages right before the RO membrane as well as at the output to monitor storage tank pressure.

The TDS probes will be placed at the Water Main / Input, after the pre-filters, after each of the RO membranes ( x2 ) and as well as after the DI Stage.

Filter minders would be for the pre-filters tracking "peformance" as if they start to build up sediment, the readings would spike and the pressure readouts would be an indication as well. The date and time is mainly there as a filter minder and more of an reminder to when the filter was replaced.

So far I have been manually flushing before every use until the TDS drops below 10PPM, and would expect the same from the automated system.

This system has been re-purposed a bit as originally it was intended for my reef, however the clean water was plumbed into a dedicated faucet by the sink and into the water feed to the fridge as well. This was achieved by a 4 way tee where the clean product is plumbed in on 1 side and then splits from there through check valves to the DI stage and to house feed. Another check valve will be installed prior to the secondary flush valve ( on the clean water line as the system has an Auto Shut Off valve which remain closed as long as there is pressure on the clean side ) which would receive another check valve behind the solenoid to stop waste water re entering the system. Both "waste" line would be feed into a 1/4" x 1/4" to 3/8" line here and would be fed into my drain.

Yes, elaborate... but the main goal is to be a set and forget system, until the filter minder goes off ( buzzer )

5

Boardburner2:
I suggest that depends on your sensors.
My current TDS project would require three digital pins per sensor.
Although it only needs one component, a capacior.

Well...

5 x TDS probes - 3 pins each 15 pins total
4 x Flow Sensors - 4 pins total
1 x Temp Probe ( I2C )
6 x Relay Trigger ( PWM ) 6 pins
1 x RTC - ( I2C )
1 x EEPROM ( I2C )

Looking at the sheer number of pins used here plus something that's 5V compatible...
Looks like the only logical choice is going to be a Mega 2560

6

Adrculda:
into the water feed to the fridge as well.

10 PPM is a bit low for consumption.

20 to 40 is generally considered safe.

75 PSI is fine without boost.
Boost is only needed in low pressure areas, in the uk 45 psi is typically the high end of the public supply.
Overpressure will rupture the membrane, mine runs at about 80 psi.

7

Boardburner2:
10 PPM is a bit low for consumption.

20 to 40 is generally considered safe.

There's an inline Ionizing Filter

[quote author=Oceanic Water Systems] IONZIED ALKALINE INFRARED pH plus and ORP negative 2.5" X 12" WATER FILTER

Ionized alkaline drinking water is saturated with negatively charged ions. These negatively charged ions attract the positively charged ions of harmful acids and neutralize them. Scientists have devised ways to measure and assign values to the electron activity. The measurement is known as oxidative reduction potential, or ORP.

What is ORP?

ORP stands for Oxydation Reduction Potential. Water either has a "positive" or "negative" ORP, measured in millivolts mV. It is the negative ORP that is beneficial to our body in that it reduces oxidation (anti-oxidant). Negative ORP is in ionized water and fresh, uncooked foods. Positive ORP increases oxidation (aging) and is found in tap water, bottled waters, distilled and reverse osmosis waters as well as cooked and processed foods.

What Does pH Mean?

pH stands for potential hydrogen. It is the measurement of hydrogen-ion concentration. The pH scale runs from 0 to 14…..A reading of 7.0 or above is alkaline and below 7.0 is acidic. The higher a pH reading the more oxygen is in the fluid you are testing and the lower the pH reading indicates less oxygen and more acid.

Acidity in the Body

The human body creates acid, all day, every day, as a byproduct of metabolism. In addition, acid is introduced into the system through eating and digestion. Many secreted and digested acids are swept away by the blood stream, filtered out by the kidneys, and released from the body in the urine. Other acids leave the body through perspiration. Your body can only process a certain amount of acids, however, so it is possible to overload the system and for the body to become acidic.

Alkaline Water Benefits

The ionization process breaks down water molecules in to micro-clusters allowing rapid delivery to cell walls for a superior hydrating effect at a cellular level. Micro-clustered water delivers nutrients to the cells more efficiently. Among several other benefits including proper hydration, detoxification, and balance in your body’s pH levels, drinking alkaline water can ultimately contribute to weight loss and anti-aging.[/quote]

Boardburner2:
75 PSI is fine without boost.
Boost is only needed in low pressure areas, in the uk 45 psi is typically the high end of the public supply.
Overpressure will rupture the membrane, mine runs at about 80 psi.

I'm not planing to use a boost pump but I figure why not make it an universal as some people might be interested to deploy such an controller and at least recover some of my time and effort that I'm sinking into making a custom shield to make things plug and play for the next person.

8

Hey what is the status of your system? There should also be Water Temperature sensor and UV control

9

+1 I have been trying to get the same setup. I have no idea what im doing when it comes to code. Any updates on your progress?