I wanted to share with you my experience with water and filtering?changing the chemistry for Bonsai. Here in Spain the TDS (total dissolved solids) can be a little high, this is primarily made up from calcium. I use a three stage filtration system, wool filter, carbon filter and then the icing on the cake a Polyphosphate filter. the last one being the main game changer. Polyphosphate coats the calcium particles and renders them unable to stick or clog anything. since using this system I have gone from Moss just refusing to grow to be coming abundant, my local Bonsai Nursey is also using this system with great success. the absolute beauty of this is that its not expensive at all. The polyphosphate fillter cost me €34. the medium needing changing around once every six months. I really wouldn’t be without this system and commend it to anyone struggling with water quality. I also for more sensitive varieties put this water into a 45 gallon drum and adjust the Ph with a Ph down solution bought from the local hydroponic shop, its super simple, just three caps of solution drops my water from 7.4 - 6.5. all you need is a PH meter easily bought from amazon for around €20. Maybe it might seem a lot of work, but I’m a big believer in the saying " you only get out what you put in " So for an investment of around €120 euros your water quality would be the best it can be in any given situation. believe me when I say that it is worth every penny.
https://www.jwsd.org/polyphosphates-what-you-need-to-know
some reading. enjoy
Wow this is super interesting! Can we see a picture of your irrigation filter setup? I’ve been wanting to do something similar to improve the tap water from the faucet. Collected rainwater would be best, but not a feasible option at this time. Do you have any concerns that with the phosphates binding up the minerals that your plants might suffer? Any evidence for leaching out of essential micronutrients? Thanks for sharing!
The polyposphate actually sequestrates the magnesium and iron making it more available to the plants. So a win win. I’ll post pictures as soon as I can.
No minerals are removed they are still available. They just can’t bind to anything
Good to know, sounds like you all are having success with the filtration system. How long have you or the nursery been putting to use?
For over a year now.
Here is a link to some information
So this could be simply fitted inline to a garden hose tap for instance?
Yes. Exactly. You have to run the system for five minutes after first installation. It’s not difficult to do.
So you just need three of the filter chambers in line. First one is a sediment filter. Second is charcoal, third is the polyphosptae.
Thank you. Will look into it. (UK)
Started looking at UK suppliers. All is available just need to sort out the quality sellers.
Hi Blown,
Would you mind posting the results of your supplier search? I live in a very very hard water area with lots of calcium in the water and my trees would probably benefit from something similar!!
Thanks!!
To be honest I never bought any in the end Chris. I went as far as looking into a good reverse osmosis system and then couldn’t fit that for various practical reasons. In discussion with somebody I trust very much I decided that I was looking too deep as I didn’t really have an issue here anyway but was just trying to add another detail.
I’m wondering whether i’m doing the same tbh!!! 
I kind of wrote off getting an RO system due to cost and the inevitable demise of my relationship if i did!! Seemed like the system above might be useful and relatively cost effective instead.
Chris. I have stopped using the Polyphospate part of filter. Over time I noticed trace element deficiencies amd had to supplement regularly. Just another headache and a squeezing the ballon effect. Try to massage a problem and it appears somewhere else!! The only effective way to reduce TDS/PPM of water is Reverse Osmosis. All other systems exchange it for something else. Whilst RO is amd can be expensive to operate, our trees can be very expensive when you start to add up the cost of a collection. Unless you TDS is very high above 225-250 or more I wouldn’t worry too much. Mine is 250 so RO was the solution for me, I mix three parts RO water with one part Tap water to get a TDS of 65-65 and a Ph of 6.5-6.9. I do believe water quality to be really important for plant health. In conclusion if it was me and cost was a consideration I would make just enough water for my best trees. Hope that helps.
Thanks for the advice Nick. According to my local water report my TDS is around 280… What RO system did you go with? There seems to be a wide range of options and prices and knowing nothing about RO as a process (although i assume its similar to dialysis and haemofiltration in humans) i have no idea what is good value or not! I could afford it, just not sure i could afford my partners reaction 
For myself Chris the cost of installing was not bad. It was the space issue(I had none) and the water wastage(I’m metered) that were considerations for me.
This is the system I use I just changed the membrane to a 100gpd. Something to remember is that it doesn’t have to be on all the time if you have made enough. Just close the supply until you ready to start again. It is a wasteful system. You can loose 4-5 gallons to make one. I’m lucky that we can use the run off for irrigation.