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Whilst I've now watched countless thunder storms not far away (within a mile or less) the total rain falling must be sub-mm for over a month. Hence with butts quickly running low the RO has been working flat out for the first time this year. Greenhouse butts now full, one other butt to go. Anyone else missing the wet stuff or have you all been lucky enough to be under a downpour or two?

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No - I'm getting a bit worried. It's not rained *properly* here for two months or more as far as I can tell. I'm down to around a quarter of water left and the forecast just shows sunshine and mid-20s for the next two weeks at least.

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I thought it was just me being ill-prepared; I have about a week's worth left in a barrel, then its weighing up using boiled water against buying deionised water.

Maybe I should organise a barbie for Saturday; it will rain then.

Edited by Chimaera

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My butts dried out a couple of weeks ago.  Luckily my water supply is my own well that has a low TDS (unusual for a well) so I just filled them again from that.  I don't like doing it when seeds are involved but it's the best I can do.  

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I've got the still going two or three times a day. I shall take a 25 litre drum of distilled water to my wife's place later.

Edited by David Ahrens

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I am desperate for rain here, my plants have had to have a drink of (pause for dramatic effect) tap water! Ah the horror. It was either that or dry and crispy plants.

I do work in a lab though and will get some ro water to tide me over. But I'm disappointed, we were suppossed to get rain over the weekend but we got nothing, just wind.

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Had a little bit of rain the other day, but I've mostly been using RO for a while now. Have to run it for 2 days to fill the butts.

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What is the cheapest effective option for rendering tapwater OK? RO units/Distiller? I have been on the edge of water supply for the CPs more often than I like, but have managed to keep afloat just about. Obviously we're not talking plumbed-in systems or push kitchen fittings, but what are the options and the sorts of prices?

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I have been trying to work out if boiling water to precipitate carbonate will reduce TDS sufficiently. Hs anyone with a TDS meter done the experiment? It appears that if there is enough calcium in solution (as should be the case in a limestone/chalk aquifer, as in most of SE England) it should be possible to get bicarbonate down to 80 TDS, at which point atmospheric CO2 levels prevent it going lower. So by this, boiling water and letting the carbonate precipitate out would work for water for the short term at least. 

Does anyone know if this is true or not?

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I'm fairly certain that if you boil the water then what you are doing is reducing the amount of water rather than the hardness as it does not evaporate. The old fishkeeping adage of 'the only solution to pollution is dilution' applies. Concentrating it will make it worse as what you will be removing is pure water. I have found, however that freshly poured tapwater has a higher TDS than that which has been left to stand overnight. The chlorine (not chloramine) having evaporated.

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My water butts are empty and I have about 500L in the IBC tank so I'm OK for a few more weeks but it's getting desperate. This weather has been great for work but not my water supply! 

Edited by Plantsman89

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The theory is that most things dissolved in water get concentrated as you boil water off, but bicarbonate is different; you drive off CO2 which is less soluble in hot water and the bicarbonate ions that were associated with it then bond with any calcium present and precipitate out as limestone, so TDS drops until you run out of calcium or CO2 levels reach that soluble in boiling water. If water has magnesium in it (there should be a lot in NE England), this does not bond with bicarbonate the same as calcium and precipitation is different. On various brewing websites the chemistry is explained far better than I can.

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Then providing you test the tds I'd say give it a go and run an experiment.  All it's gonna cost is the electric to boil the kettle.

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I have about 18 days left and the forecast is not looking good for rain,

I put in extra 210 litres butt last year because nearly run out last year

thinking of doing the red indian rain dance soon that's if you can

find me some red indians lol

 

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All my plants are living outside while I prepare the ground for their new greenhouse. They're in the shade all morning just to try and keep transpiration low, so this year is a write off for colour (and storm Hugo flattened a few pitchers). 

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On ‎6‎/‎21‎/‎2018 at 10:05 AM, Richard Bunn said:

Then providing you test the tds I'd say give it a go and run an experiment.  All it's gonna cost is the electric to boil the kettle.

This intrigued me, so I've tried it!

We have a water softener, so it was possible to test both hard and softened water before and after boiling. The water was boiled in a kettle, just once. Here's the results from my TDS hand held meter. 

Hard water before boiling 259 ppm, after boiling 268 ppm.  Softened water before boiling 276 ppm, after boiling 311 ppm.

No idea why the increase was so much greater for the softened water compared to the hard water.  Others may be able to shed light on this.

It would seem boiling isn't a good idea.  No doubt the increases would have been even greater if the water had been left to boil for any length of time.

Guy

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3 minutes ago, Guy said:

This intrigued me, so I've tried it!

We have a water softener, so it was possible to test both hard and softened water before and after boiling. The water was boiled in a kettle, just once. Here's the results from my TDS hand held meter. 

Hard water before boiling 259 ppm, after boiling 268 ppm.  Softened water before boiling 276 ppm, after boiling 311 ppm.

No idea why the increase was so much greater for the softened water compared to the hard water.  Others may be able to shed light on this.

It would seem boiling isn't a good idea.  No doubt the increases would have been even greater if the water had been left to boil for any length of time.

Guy

Interesting. So the theory is not matched by the results. It may be that your water contains sulphate which is not removed by boiling. I think at least some water softeners replace calcium with sodium; it may be that if you boiled in a kettle with limescale in it you reversed the reaction, with the addition of losing some water. My chemistry is not up to thinking why.

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You have two types of hardness in water; temporary (sometimes called carbonate hardness) and permanent.

They are caused by different dissolved minerals and although both are readily soluble in water, only temporary hardness is removed by boiling.

The only way to remove permanent hardness is via an ion-exchange resin and/or reverse osmosis membrane. 

However;

With regards to the differing tds values, it is important to remember that soft water is not the same as pure water. i.e. TDS is a crude measurement of how pure water is, not it's hardness or relation to any one specific molecule. 

With a simple water softener that works by ion-exchange, as the name implies, the hard water causing Calcium & Magnesium ions (Ca2+ Mg2+) within their suplhates and chlorides are replaced with other ions, mostly Sodium (Na+). Therefore softened water will still contain lots of dissolved solids and be impure, just different ones and crucially not the 'hard water' solids anymore. 

With your kettle scenario, I'm guessing that the resin in the softener has already exchanged the Ca & Mg ions, not only from permanent hardness but also across the board including the carbonate hardness too. Boiling drives off the pure water as steam, leaving behind impure water in both case, but, in the tap hard water, the temporary hardness is precipitating out as solids whereas nothing is precipitated out of the softened water,  thus just concentrating the Total Dissolved Solids as the water evaporates.

A reverse osmosis membrane or distillation setup is the way to obtain pure water, i.e. one with nothing dissolved in it. RO by physically screening the molecules out, and distillation by recapturing the pure water steam and discarding the leftover original impure water.

Hope that clarifies, I may not have explained that perfectly!

Edited by Stu
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I might buy my wife a reverse osmosis unit. I am sure that Amazon will supply these. Any recommendations ? or are they all much of a much. I take it that you have to run them every so often to keep the membrane healthy.

Edited by David Ahrens

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Just had a quick butchess on Amazon. There quite  a lot to choose from and some are not very expensive. Some are 3 stage, some are 6 stage. Is there much difference ? Especially when you are only watering CP's.

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The stages relate to the individual processes of filtration and although fairly straightforward, different manufacturers explain differently and try and upsell their kits by promoting more stages than they have or necessary, which just adds confusion!

The first stage is a sediment filter, with fine material that will screen out particles above a certain threshold size (things like fine sand and grit). The second stage is activated carbon and will remove chlorine and other simple chemical traces and odours from the water.

Stopping there would be a simple 2-stage filter,  and whilst would improve drinking water slightly, it would not be any good for CPs.

The third stage is a Reverse Osmosis (RO) membrane filter. This is the main process filter and will reduce the TDS down to levels suitable for CPs (usually under 10ppm, but can creep up with a dirty filter).

The first 2 stages MUST be present in an RO unit otherwise the contaminants will quickly foul and block the membrane, thus you should never run an RO of less than 3-stage.

The units are described as 25/50/75/100/150 (etc.) GPD... this refers to the membrane size and theoretically how many (U.S.) gallons of RO water it can produce per day (24 hours). The actual throughput will be lower than this based on length of piping, mains water pressure, condition of membrane etc., but it is a good ballpark figure to work out what size you need. You pay more and replacement filters are more for the higher rated systems, but they produce water faster.

The addition of a DI (De-ionisation) resin stage, after the RO membrane is highly advised as it further cleans up the water and removes any last traces from the output, getting the water down to a pure 0ppm TDS. This will be called a fourth stage or sometimes 3-stage+DI.

Incidentally I have a 75 GPD 3-stage+DI and am very happy with it... It's a lifesaver.

When companies advertise a 5, 6 (or more!) stage system, they are referring to additional carbon or sediment filters, either before or after the RO membrane and will claim to improve even further but it's basically snake oil. Unless you are inputting very filthy water (i.e. that would never pass through water mains) then additional filters are unnecessary. Also, post DI stages are usually used in drinking water (under sink) units and actually usually re-introduce minerals to improve drinking taste, which would be counter productive to CP use.

In terms of maintenance, there are a few things you should do if you want to keep it running efficiently and prolong the membrane life for as long as possible before replacement;

  • They don't survive frost and freezing temperatures... if operating in greenhouse/outbuilding, make sure you either bring it inside during the winter or very thoroughly insulate the entire unit by some means.
  • They don't survive frost and freezing temperatures... if operating in greenhouse/outbuilding, make sure you either bring it inside during the winter or very thoroughly insulate the entire unit by some means.
  • The membrane benefits from a flush at regular intervals. This is easily done by installing a flush kit which bypasses the flow restrictor and pushes water quickly through, dumping almost all as waste but importantly carries away anything that may have previously been clogging the RO membrane. It's advisable to flush for a minute or so every month (or after so many gallons if you are using heavily). Also a long flush is needed if the unit hasn't been used for a length of time.

  • The membrane (once first used) should never be allowed to dry out. This is most easily achieved by adding ball valves close to the unit on the input and output pipes, so you can easily shut off the unit, trapping water within when it is not in use.

  • Filters (sediment/carbon) are recommended to be replaced every 6 months-1 year, but depends on how much water you produce and quality of input water from mains. If the filters fail to remove contaminants, the RO membrane will not last long.

Look on ebay for a few trusted sellers on there. That's where I got mine from and the prices are good.

Edited by Stu

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Just bought a second water butt and now am going to Halfords to buy 50 litres of Deionised water to get me through until sunday when rain is forecast.:rolleyes:

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ok so we are all running short of rainwater .So I have a question is can  DE-IONIZED water( eg as used for car batteries )  be used on Cps or must it be Pure distilled water or R.O water

Cheers

Edited by tatter

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48 minutes ago, tatter said:

ok so we are all running short of rainwater .So I have a question is can  DE-IONIZED water( eg as used for car batteries )  be used on Cps or must it be Pure distilled water or R.O water

Cheers

I used de-ionized for a brief period when first getting into CPs but I have read conflicting information on its suitability.

As someone who isn't able to collect rainwater I simply use RO water from a local Aquatics store for about 15p per litre. This could be worth considering until we get more rain.

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