To join the tanks I ordered 4 Overflow Tank Connectors 22mm
This has a 22mm thread on it, which is the same as the one that a washing machine uses.
So I ordered some 80 micron stainless steel mesh
after seeing some filters built into 22mm washers for washing machines.
Consequently I have also got some 22mm connection tubing
I got a couple of plastic containers to use as growing tanks for an ebb & flow setup from Wilkos. It says £5 there, it said £ on the shelf in the store but at the till they were £3.99
The plan is to pump water from a store into one of them through 10mm pipe and have a 22mm overflow connector feed the second one and another 22mm overflow exit that one and return the water to the store. This means that the containers won't overflow.
A second overflow connector in the bottom of each one container will feed into the solenoid valve I ordered yesterday. This will be activated for the drain cycle to make sure that the water stock is completely removed. The water removed in the drain cycle is filtered through an 80 micron passed into the recycling phase where nutrients and pH are set to appropriate levels and other processing such as uv exposure for removing biological pathogens such as pythium can take place.
Separating the flood store from the recycling phase means that the pH and ppm probes can be utilised across multiple growing areas. The probes are the most expensive parts of the system so this reduces costs when scaled. The UV can also be used across growing areas.
The tanks and connectors in the "grow room"
Putting yesterday's bits together. I have the relay gaffer taped into a pop bottle and the pump sitting in a 25 litre bucket. I have checked that the pump runs from energising the relay. All good.
Time to write to code for the NXP. First off for sensor testing purposes is to get the TCP / IP running. The simple UDP sender already found a checksum bug in the supplied library. Oh well, at least the packets still show up in Wireshark. Let's hope TCPSERVER on Linux will ignore it.
Off to Wickes / B&Q now to find some plumbing bits.
The flow meter is specced at 3/8" push on fitting so that's a good place to start because the pumps have no specification given.
Having looked it it, it might make sense to think about some clips but lets not spend cash needlessly for now, wait for normal cables ties to fail.
The flow meter also says that it should have a pre-filter for 80 microns, that is 0.08mm. "Mesh 200" is 0.075mm so this size is the most appropriate.
I have found some mesh on ebay which is £2.99 per 15cm x 15cm sheet but there are also various inline ones, a fuel filter for instance but that's £17.99
There are three acids listed in Resh's hydroponic book
The trouble will be to find a suitable hose that is acid resistant.
The peristaltic pumps come with silicone tubing and for this the news is not so good. Because of that I have included citric acid in the list.
| Acid 20 °C | PVC | Silicone |
|---|---|---|
| Nitric | up to 50% | Maybe - test it |
| Sulfuric | up to 95% | No |
| Hydrochloric | 50% - concentrated | No |
| Phosphoric | up to 85% | Maybe - test it |
| Citric | 10% - Saturated | Excellent |
It seems a citric acid solution is preferable for my uses.
