# Cost of RO?



## jameson_uk (28 Feb 2020)

My water out the tap is about GH12 / KH5 / TDS ~320 and whilst in theory this is meant to be find for Cherry shrimp I lost the first two colonies I attempted to setup.   For the third attempt I mixed 2/3 tap with 1/3 deionised water and this has proved fruitful and now I have a lot of breeding shrimp.

This is fine but I am have been looking at ways of cutting down the amount of plastic I am getting through (I am using Tesco deionised water at £1.5 for 2.5l) and potentially switching my other tanks to a similar mix.

I would love to use rain water but living on the very edge of Birmingham I daren't.   Nearest LFS selling RO is quite a way away and whilst I believe there is a Spotless Water site closer, this would still be a pain having to travel every time I needed water (and I don't believe I can leave RO water to stand around too long?)

I keep looking at some RO units like https://www.pro-shrimp.co.uk/water-...mpact-130-ro-filter-system-4001615070392.html which at £60 don't seem too expensive but I am looking at how much these things cost over time.   I am not on a water meter so the cost of the wasted water isn't an issue (although I am just switching the plastic issue to a water wastage one ).   I know you need to replace the membrane every so often but I cannot seem to find replacement parts only generic ones.   Is there anything else that is consumable and needs replacing?   

Basically other that the cost of water, what is the running cost for an RO unit?

Also can you do anything with the water that is not used by the RO unit?   I am guessing that this will be really really hard water so won't be useful for fish tanks?


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## lazybones51 (28 Feb 2020)

I use a combination of LFS (Maidenhead Aquatics) and Spotless water for RO (if I know I'll be driving close to one).

Maidenhead Aquatics is £3 for 25L and Spotless water about 4p a litre (so about £1 for 25L). I fill up three 25L containers at a time which last me around 6 weeks (25L water change a week 50% RO & 50% Tap). I haven't had any issues with storing water for this length of time. Think how long the DI water you buy from Tesco could potentially have been sitting in those plastic containers.


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## Siege (28 Feb 2020)

Defo spotless water. Just checked and they have one in Birmingham.

https://spotlesswater.co.uk/

If they are close I wouldn’t even bother trying to make RO water


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## jameson_uk (28 Feb 2020)

Siege said:


> Defo spotless water. Just checked and they have one in Birmingham.
> 
> https://spotlesswater.co.uk/
> 
> If they are close I wouldn’t even bother trying to make RO water


I live about 11 miles away from the central Birmingham site which I think is roughly the same as to LFS that sells RO (but that is much more accessible).
There is a Sutton Coldfield site which says it is coming soon (but has been saying this since I looked a few years ago) and tbh I thought this was open.



lazybones51 said:


> I use a combination of LFS (Maidenhead Aquatics) and Spotless water for RO (if I know I'll be driving close to one).
> 
> Maidenhead Aquatics is £3 for 25L and Spotless water about 4p a litre (so about £1 for 25L). I fill up three 25L containers at a time which last me around 6 weeks (25L water change a week 50% RO & 50% Tap). I haven't had any issues with storing water for this length of time. Think how long the DI water you buy from Tesco could potentially have been sitting in those plastic containers.


I can't remember where I read about not leaving RO for ages but I always assumed the fact the Tesco stuff is sealed and in a non translucent bottle made it last longer than it would in most the reasonably see through 25l containers I see (and the ones LFS gives you when you buy first RO).


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## alto (29 Feb 2020)

Yes, RO does/can go “off” - and you’re unlikely to see the presence of increased pseudomonas bacteria (more of an issue with RO/DI water stored at warmer temperatures) etc
Obviously the use of sterile containers and an industrial grade UV on the RO system will minimize bacterial etc growth

RO System itself may become contaminated (hence the inclusion of antibacterial components in membranes, constant flow, back flushing etc) ... several local grocery shops had their systems shut down and replaced over this issue (as shop personnel had no clue about system maintenance)

If you store RO water in plastic containers, it will leach plasticizers into the water (you may find this more/less a consideration) 

As for the linked RO system, *pressure of 4 bar* is required for the reported outflow, so you may need a booster pump, check on the costs of replacement parts, and expected RO lifetime based upon your input water, also water wastage 
(many systems will run a macro type DI cartridge ahead of the RO cartridge to improve water throughout and RO membrane longevity, if you have particles in your tap water, you may want to prefilter the water for same)

Not to dissuade you from purchase


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## jameson_uk (29 Feb 2020)

alto said:


> As for the linked RO system, *pressure of 4 bar* is required for the reported outflow, so you may need a booster pump, check on the costs of replacement parts, and expected RO lifetime based upon your input water, also water wastage
> (many systems will run a macro type DI cartridge ahead of the RO cartridge to improve water throughout and RO membrane longevity, if you have particles in your tap water, you may want to prefilter the water for same)
> 
> Not to dissuade you from purchase


It is the cost of spare parts and was mainly interested in along with how often things need replacing.   I couldn't seem to find any Dennerle  official replacement parts for sale (which did slightly worry me).

Hadn't looked at the pressure requirements.   That said I don't need huge volumes so lower flow isn't too much of an issue (or would running it at a lower pressure reduce the efficiency?)


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## mort (29 Feb 2020)

I'm not sure about this exact ro unit as I'm unsure if those are standard sized pods but in general replacement filters are cheap. As it's a three stage I'm assuming it's a carbon filter (normally a £5ish replacement), sediment filter (even cheaper than carbon) and then the membrane (priced depending on the rating but about £15 or so for a 50 gpd).
The amount you have to replace them really depends on how much you run the unit. If your making a couple of hundred litres a week you might need a new membrane every year and carbon and sediment filters maybe twice a year but you tell when they need replacing by monitoring the waters tds on output. As I run marine I also use di resin and this is the biggest cost for me.

Low pressure does increase water wastage and it can be by a large amount. These filters are generally that efficient anyway but all the water that is wasted on my unit goes into a water butt that waters my vegetable and fruit plants.

You can buy blue 25l barrels to store your ro and ime you can easily keep ro water this way for a month or so as long as the lid is tightly sealed. I had many people that I only saw once a month/six weeks that came in for water and personally if you aren't using much then I would just buy it and store it somewhere cool and dark as ro units are great if you need a lot of water but you will flood your house at least once, they give off awful condensation in the winter from the freezing water and they are only cheaper if you use a fair amount.


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## MWood (29 Feb 2020)

I live in east London and use rainwater without any issues. I did use to carbon filter it, but now I just check if the daphnia etc in the water butt are still alive.


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## Akmaliano (5 Mar 2020)

lazybones51 said:


> I use a combination of LFS (Maidenhead Aquatics) and Spotless water for RO (if I know I'll be driving close to one).
> 
> Maidenhead Aquatics is £3 for 25L and Spotless water about 4p a litre (so about £1 for 25L). I fill up three 25L containers at a time which last me around 6 weeks (25L water change a week 50% RO & 50% Tap). I haven't had any issues with storing water for this length of time. Think how long the DI water you buy from Tesco could potentially have been sitting in those plastic containers.



cheers for the info about Spotless water! Never heard of them before for some reason. Looked them up and found that there's a filling station in my town. Went there today, filled up 50L for about £2.. Cheap as chips and so straightforward to fill up. Even considering I change about 100L of water per week I think I'll be using them from now on now instead of messing with my water butt and rainwater etc. I'll be mixing it with tap water 50/50 so will cost me about £8-10 a month. Not bad I think.


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## lazybones51 (5 Mar 2020)

Akmaliano said:


> cheers for the info about Spotless water! Never heard of them before for some reason. Looked them up and found that there's a filling station in my town. Went there today, filled up 50L for about £2.. Cheap as chips and so straightforward to fill up. Even considering I change about 100L of water per week I think I'll be using them from now on now instead of messing with my water butt and rainwater etc. I'll be mixing it with tap water 50/50 so will cost me about £8-10 a month. Not bad I think.


You're lucky having one so close .


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## Akmaliano (5 Mar 2020)

lazybones51 said:


> You're lucky having one so close .


definitely. just ordered another 4 25l jerry cans too  

do you know if mixing it 50/50 with my tap water which is very hard at about 15GH would be ok? I'm not after a super pure clean water but just want to reduce the hardness a bit. Would 50% be enough, or too much? I've got no experience on this so would really appreciate some advice.
thanks!


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## Nick potts (5 Mar 2020)

jameson_uk said:


> It is the cost of spare parts and was mainly interested in along with how often things need replacing.   I couldn't seem to find any Dennerle  official replacement parts for sale (which did slightly worry me).
> 
> Hadn't looked at the pressure requirements.   That said I don't need huge volumes so lower flow isn't too much of an issue (or would running it at a lower pressure reduce the efficiency?)



The frequency of replacement will depend on your incoming water TDS. Mine is only around 70 and my filters last a while.

As a general guide, the prefilters should be changed every 6 months or so and the actual RO membrane maybe yearly (i have gotten a lot longer), and the DI if being used should be changed as soon as the TDS going over 0

I don't use RO on my freshwater tanks, but do with my reefs, I use a compact system with DI like this one https://www.finerfilters.co.uk/fine...ilter-for-tropical-marine-discus-100-gpd.html


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## jameson_uk (5 Mar 2020)

Do you need to buy specific replacements or are they all standard and generic?

I have not seen any Dennerle spares for sale which makes me think I would be having grief in six months when I want to replace the prefilter.  

My TDS is ~320 out the tap.  Would the _waste_ be good for anything other than watering plants?


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## Nick potts (5 Mar 2020)

jameson_uk said:


> Do you need to buy specific replacements or are they all standard and generic?
> 
> I have not seen any Dennerle spares for sale which makes me think I would be having grief in six months when I want to replace the prefilter.
> 
> My TDS is ~320 out the tap.  Would the _waste_ be good for anything other than watering plants?



As long as the membrane is rated correctly (so buy a 50gpd one for a 50gpd unit then generic is fine), same with prefilters, it's based on the housing size so 4in filter etc.

Waste is not really good for anything really, except like you say, the plants


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## Ed Wiser (5 Mar 2020)

Ro systems are based on standard filter canister sizes. So they can have the same filter element inside. 
The Ro filter is the same in the vast majority. It is a DuPont RO Filter element.  Everyone start’s by getting water and lugging in home. It gets old after a while. It is pretty nice beings able to make water when ever you want. 
An Ro/DI Filter lets you control your aquariums water parameters.


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## lazybones51 (5 Mar 2020)

Akmaliano said:


> definitely. just ordered another 4 25l jerry cans too
> 
> do you know if mixing it 50/50 with my tap water which is very hard at about 15GH would be ok? I'm not after a super pure clean water but just want to reduce the hardness a bit. Would 50% be enough, or too much? I've got no experience on this so would really appreciate some advice.
> thanks!


I don't have much experience myself . However I was struggling to grow some plants and had read about hard water being a factor (my tap water has a TDS of 570 last time I checked) so I went down the 50/50 route just to see if anything improved.


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## sparkyweasel (5 Mar 2020)

lazybones51 said:


> I went down the 50/50 route just to see if anything improved.


Did it?


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## lazybones51 (5 Mar 2020)

sparkyweasel said:


> Did it?


Yes, it made a big difference. I'm now having success growing various Rotala species which previously grew stunted in an identical setup.


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## Tom Ryan (@aquascaperay) (5 Aug 2020)

I've had my Ro unit for over 3 years and it's still going great. The main cost is ever 6 months I replace the pre filter membrane and fill up with deionisation resin. Other than that it's a lot cheaper in the long run than going to your LFS


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## jaypeecee (5 Aug 2020)

Hi @Tom Ryan 


Tom Ryan said:


> I've had my Ro unit for over 3 years and it's still going great. The main cost is ever 6 months I replace the pre filter membrane and fill up with deionisation resin. Other than that it's a lot cheaper in the long run than going to your LFS



Could you let us have a few details of your RO unit and setup?

I see that you're in Berkshire. I'm in Bracknell. My LFS of choice is the MA Ascot branch at Windlesham.

TIA.

JPC


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## Tom Ryan (@aquascaperay) (5 Aug 2020)

Hi @jaypeecee,
I currently own a Ada 90f tank so I went for the 50gallon per day Ro unit from osmotics and look to fill up one 25L water butt for each water change (takes about 45 mins to do through my bath tap at around 50% efficiency). You can find the unit here https://www.osmotics.co.uk/products/3-Stage-50-Gallon-Per-Day-Reverse-Osmosis-System.html I would recommend getting in touch with them as there's a few connecting parts you need plus also a tds meter is useful. Hope that helps


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## jaypeecee (5 Aug 2020)

Hi @Tom Ryan 


Tom Ryan said:


> Hope that helps



Yes, it does. I'm not intending to make a purchase anytime soon. I used to have an RO unit a few years ago but throughput was hopelessly slow as I didn't use a booster pump. And, I'm now on a water meter - so, efficiency of the system needs to be as high as possible.

Thanks a lot.

JPC


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