# RO unit worth it?



## Brad123 (14 May 2021)

I live in Oxfordshire lovely hard water is it worth buying a ro unit?  I like the idea of 1 but will it help or make things complicated?


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## foxfish (14 May 2021)

RO units waste so much water like 80-90%, that for me means I am not a fan but, it is possible to save the waste water for other uses!
Rain water might be an option for you?


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## MrClockOff (14 May 2021)

Brad123 said:


> I live in Oxfordshire lovely hard water is it worth buying a ro unit?  I like the idea of 1 but will it help or make things complicated?


I’d recommend to try Spotless Water. I’m personally using it for about 1.5 years, consistent 0 TDS from their hose and haven’t encountered any issues so far. The price depends on the location but in Bournemouth the cost is 1.5p per litre. 
PM me if interested. I think if I’d recommend someone we both would get about £20 credit each.


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## papa_c (14 May 2021)

My RO unit has dual membrains and has a waste to production ration of around 1.5:1, still some waste but not 90%.

Produces water with tds of 12


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## Conort2 (14 May 2021)

All depends what fish you’d like to keep, size of the aquarium etc. If you had a Malawi cichlid tank or rainbow fish for example it would be useless. An aquarium with wild caught South American species then it would be a differrent story.

cheers

Conor


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## MichaelJ (15 May 2021)

papa_c said:


> My RO unit has dual membrains and has a waste to production ration of around 1.5:1, still some waste but not 90%.
> 
> Produces water with tds of 12


My RO system with a single membrane is claimed to be  1:5  (5 liter of waste to 1 liter of "pure"  water)  @ 25C (77F)  and 60 PSI of water pressure.... However, at lower pressure and lower temperature the efficiency goes way down... right now (spring in Minnesota) I am probably getting somewhere around 1:8 ... in the depth of winter it's more like 1:12... so it really depends.  TDS however, is constant... with a brand a new membrane I'm getting 2-3 TDS ... right now my RO water is around 4-5 TDS regardless of water temp.

Cheers,
Michael


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## Tom Michael (15 May 2021)

I would say depends on why you want one? If it’s for plant growth I would say not. I would say much more important is optimising Co2. You will likely use more co2 with harder water but the vast majority of plants won’t care on the hardness of the water.


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## Brad123 (15 May 2021)

Cheers all for the reply’s.  should of explain a bit better was thinking more on the water quality side.  To get the right GH and KH is that worth it for the plants.
The tank is only a 65ltr at the moment doing daily water changes(tank 2 weeks).
 I work at a power station so can get 0 TDS water but it’s a pain to get home. That’s why I was looking at ro units.


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## Brad123 (15 May 2021)

Tom Michael said:


> I would say depends on why you want one? If it’s for plant growth I would say not. I would say much more important is optimising Co2. You will likely use more co2 with harder water but the vast majority of plants won’t care on the hardness of the water.


Ok thanks that’s what I was after
Cheer Brad


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## dw1305 (15 May 2021)

Hi all,


Brad123 said:


> The tank is only a 65ltr at the moment doing daily water changes(tank 2 weeks).


Is <"rainwater an option?"> I've used it since the 1970s <"without any problems">. 

cheers Darrel


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## shangman (15 May 2021)

I have a 60L tank which is filled with rainwater. I have 2 20L jugs which I fill either in my garden or at the allotment, to do a 30 - 50% change a week (I don't use CO2, so each jug lasts me a week). My plants do grow pretty well in it, but not as well as tap water and CO2. I use rainwater because I like to keep softwater fish, I have another tank with tapwater and shrimps and the plants grow just as well. If you want a really amazing hightech tank with loads of fancy Dutch-style stems then I think softwater does help. You'd only need 1 big waterbutt to collect enough water weekly for it, if you have a garden and a roof of any kind it's really easy to do!


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## Tim Harrison (15 May 2021)

Seriously, you don't need to use RO water even in hard water areas. Most plants really don't care. @Aquarium Gardens in Huntingdon use super hard tap water, the plants are all very healthy and the tanks stunning.


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## ceg4048 (15 May 2021)

I agree with Tim. It is absolutely pointless to worry about "right" GH/KH as this has nothing to do with plant health and has no effect on ability to inject CO2.
These plants were grown in typical hard water in excess of GH 26. What plants and fish care about is clean water.



Cheers,


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## Brad123 (15 May 2021)

dw1305 said:


> Hi all,
> 
> Is <"rainwater an option?"> I've used it since the 1970s <"without any problems">.
> 
> cheers Darrel


I’ve got a water butt  need to connect it back up.  But think will stick to tap water for now it just easier and if the plant don’t mind it even better.
Cheer all for the reply’s
Brad


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## Tim Harrison (15 May 2021)

Like Clive mentions, clean water is paramount. What usually happens when using RO is water changes become a PITA, and they tend to become less frequent. And the tank suffers. Better to use good old tap water and change it frequently.


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## castle (15 May 2021)

ceg4048 said:


> What plants and fish care about is clean water.



I’d disagree with this a touch, fish do care about water hardness.


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## Aqua360 (15 May 2021)

castle said:


> I’d disagree with this a touch, fish do care about water hardness.



Why just a touch, it's pretty fundamental that water hardness plays a large role in fish health.


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## castle (15 May 2021)

Aqua360 said:


> Why just a touch, it's pretty fundamental that water hardness plays a large role in fish health.



As I agree about plants but about the fish 👍


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## Tim Harrison (15 May 2021)

Obviously, if you’re trying to breed soft water species it’s important, but otherwise not so much.


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## castle (15 May 2021)

Alrighty, here is the hill I die on.

I believe fish suffer when they’re at an extreme, my way the water is very very hard, you can’t enjoy some F1 discus, they all wither away, especially true for the wild neons and smaller Ls - of course they live, in some cases for a handful of years, but not 10 like a happy discus in that sweet soft water, it’s not a full life. On the flip side, lamprologus in some soft water and they’ll be slowly dying too - I don’t know why that way round. There’s a few reasons in hard water why soft water fish suffer, primarily it’s internal organs aren’t used to all those minerals in the water and kidneys fail. Eggs can’t break down their membrane.

Of course, spawning can be seen as benchmark for fish health, but saying only match water requirements if you want them to breed is cruel.


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## MichaelJ (15 May 2021)

Tim Harrison said:


> Obviously, if you’re trying to breed soft water species it’s important, but otherwise not so much.


There is no way I would keep Dwarf Cichlids from the Amazon Basin at the same water parameters (including water hardness) I used to keep African Rift Lake Cichlids ... That said, most fish, especially fish bred in captivity, have a far higher tolerance to a much wider range of water parameters than most tend to believe. That said, I don't think its distraction from the hobby of fish keeping to at least be in the _ballpark_ of the water parameters found in the fishes natural habitat - and see no reason why the fish would not be better off with that.

Cheers,
Michael


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## castle (15 May 2021)

MichaelJ said:


> There is no way I would keep Dwarf Cichlids from the Amazon Basin at the same water parameters (including water hardness) I used to keep African Rift Lake Cichlids ... That said, most fish, especially fish bred in captivity, have a far higher tolerance to a much wide ranger of water parameters than most tend to believe. That said, I don't think its distraction from the hobby of fish keeping to at least be in the _ballpark_ of the water parameters found in the fishes natural habitat - and see no reason why the fish would not be better off with that.
> 
> Cheers,
> Michael



I missed that in my post, hobby bred, or fish farm bred tend to be a lot more tolerant 👍


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## glasscanvasart (15 May 2021)

I don’t know where I sit on the idea that (captive bred) fish need the right kind of water. I’ve killed a number of fish prematurely and I can’t help but wonder if it’s because of the water parameters. Though I do suspect that they were underfed, as I took the advice that the fastest way to kill fish was to overfeed them a little too seriously. Then again I’ve unintentionally bred poropanchax normani in rock hard water, so I’m really not sure. 

At the end of the day I think I’ll probably start using RO or rainwater in the future when I start to keep tetras and cichlids (some wild caught). I just don’t think I would feel comfortable providing them with suboptimal conditions. There’s also the inconvenience of salt creep, but as far as plants are concerned, it doesn’t matter.


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## Tim Harrison (15 May 2021)

For sure, if we’re talking extremes and particular species with exacting requirements you’re very probably right. But that’s not what I was getting at and I don’t think that is within the experience of the average hobbyist.

It could also be that we are attributing cause and effect wrongly. I’ve had plenty of wild caught soft water fish live beyond what is deemed to be their natural lifespan in hard water, and happily without apparent stress. Water quality is probably of equal or greater importance. Perhaps there are other confounding factors we’re not necessarily aware of.

And something else that has always puzzled me... How come captive bred so called soft water fish are thought to be more tolerant of varying water quality, hard or otherwise? Do their genetics suddenly and drastically change simply because they are bred in hard water, for instance? I very much doubt it; that's dangerously close to Lamarckian evolution.

Fish are probably more adaptive to different environmental conditions than is perhaps commonly thought. Many aquatic habitats are subject to a range of hydrological conditions from flood to drought during wet and dry seasons for instance. The species that live in them in turn experience a range of chemical and thermal changes. But of course South American dwarf cichlids ain’t going to be happy kept in the same conditions as African Rift Valley cichlids and vice versa.

Also spawning doesn't necessarily indicate optimal water conditions, just as lack of spawning indicates sub-optimal conditions. Rather certain changes in water parameters will trigger spawning. Changes which fish associate with conditions likely to give their offspring the greatest chance of survival. For instance, many tetras breed during the rainy season.


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## MichaelJ (16 May 2021)

Tim Harrison said:


> And something else that has always puzzled me... How come captive bred so called soft water fish are thought to be more tolerant of varying water quality, hard or otherwise? Do their genetics suddenly and drastically change simply because they are bred in hard water, for instance? I very much doubt it; that's dangerously close to Lamarckian evolution.


I do not know the answer, and it probably depends on the species of fish as well, but I suspect it might have to do with the selection process over time of the specimens breed in captivity that gets to dominate the breeding stocks, trade and eventually ends up at the LFS - as opposed to much slower natural (Darwinian) selection… Unfortunately, there is also a lot of inbreeding taking place which tend to impede biological fitness so that somewhat goes against the idea that fish bred in captivity should be hardier.



Tim Harrison said:


> Fish are probably more adaptive to different environmental conditions than is perhaps commonly thought. Many aquatic habitats are subject to a range of hydraulic conditions from flood to drought during wet and dry seasons for instance. The species that live in them in turn experience a range of chemical and thermal changes.


That is my belief as well. 

Cheers,
Michael


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## castle (17 May 2021)

Sorry I didn’t respond to this sooner; my response required a little more thought and also a keyboard on that iPad isn’t something I enjoy typing on.

I am unable to explain it; but I have seen it - some fish with minor adjustments to water params will effectively become okay over time in water they’re not particularly preferring. Now these fish aren’t extreme requiring fish, I mean wild guppy coming in with a request for super high gH then for their many times removed offspring to be fine in pond water! Imagine how many discus died to get that new strain that is alright in hard-ish water?! I'm saying, it certainly is possible to breed in some tolerance - but I can't explain it.

Fish died in my water as a kid for years, until I started using collected water (from a stream, pond, and gutter - I know!).   I mentioned in an earlier post “extremes” as it protects me somewhat from having to make lots of justification and references as extremes are fairly well documented. Intolerances of fish which are closer either side of the mid point w/neutral pH is a bit harder to prove - as in I cannot.


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## ceg4048 (17 May 2021)

castle said:


> I am unable to explain it; but I have seen it - some fish with minor adjustments to water params will effectively become okay over time in water they’re not particularly preferring. Now these fish aren’t extreme requiring fish, I mean wild guppy coming in with a request for super high gH then for their many times removed offspring to be fine in pond water! Imagine how many discus died to get that new strain that is alright in hard-ish water?! I'm saying, it certainly is possible to breed in some tolerance - but I can't explain it.
> 
> Fish died in my water as a kid for years, until I started using collected water (from a stream, pond, and gutter - I know!).   I mentioned in an earlier post “extremes” as it protects me somewhat from having to make lots of justification and references as extremes are fairly well documented. Intolerances of fish which are closer either side of the mid point w/neutral pH is a bit harder to prove - as in I cannot.


I agree with Tim. How does anyone know what a fish died of? Are autopsies performed to determine cause of death? Can anyone pin the cause directly to Calcium/Magnesium concentration in the water? Also, what is the mechanism of the damage done?
People assess blame based on their favorite boogieman. From EPA and other environmental agency studies we know the #1 killer of fish historically is hypoxia due to water pollution. We also know that folks often refuse to change the water in their tanks for reasons of "keeping parameters the same" which is another myth. Can the two be related? I reckon so. I don't have any trouble keeping fish alive long term in hard water, whether it be discus or dwarf chiclids. There are as many ways to kill fish as there are the number of hobbyists out there, and as mentioned, fish have a wide range of adaptability. Pet shops stayed in business for years on end specifically because hobbyists could not keep their fish alive for a multitude of reasons, mostly overcrowding, overfeeding and the resultant foul water.
Hobbyists assume that just because they have a filter then that automatically means their water is clean, but this isn't true. Unremoved waste continues to damage the inhabitants. People really need to focus on cleanliness instead of on "water parameters".

Cheers,


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## castle (17 May 2021)

Hey, @ceg4048 of course we cannot be certain of what is killing a fish. I’m posting to make note that soft/hard water fish can slowly die when they’re not in water that matches what they prefer. Of course they adapt, some better than others.

Because I cannot prove (scientifically) any of this, I’m just going by experience. I agree with a lot of what you’re posting, but can we not disregard water hardness as a cause of fish deaths?


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## sparkyweasel (17 May 2021)

ceg4048 said:


> Hobbyists assume that just because they have a filter then that automatically means their water is clean,


Not only an assumption, but there's also a huge amount of marketing aimed at selling us ever more expensive and complicated filters.


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## PARAGUAY (18 May 2021)

All l can add is the chap l know with the Discus fish house used RO water although he did have water butts scattered about. Most tanks had what looked like German Discus feature tank had a dozen or so Wild Discus so l suppose he wasnt going to rely on the utility companys with a few thousand pounds of fish .


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## jameson_uk (18 May 2021)

My water is GH12 / KH5 and I ended up with an RO unit as I was buying distilled water to drop the hardness slightly for the shrimp I keep.
Concerned about waste etc, I got a pumped model which should of cost about £140.   As the seller was absolutely useless Amazon ended up refunding me.
This unit seems to waste about 50% (so it takes 20l of tap water to make 10l of RO) which isn't too bad.

I have never got around to using it in my main tank and to be honest I doubt I ever will as it would be a right faff to produce the RO and use this to change 90l of water.
In the shrimp tank I use 1/3rd RO and 2/3 tap which drops the GH to about 8 and I top up any evaporation with RO.    I know RCS should be fine in GH12 water but after loosing two colonies to what appeared to be molting issues I think the fact they were probably bred for many generations in remineralised RO means they are not as hardy as they used to be (and the one thing I have found is that they do not like big changes at all).

I would only consider buying one if your livestock dictates it (Wild fish, delicate shrimp, things like Chocolate Gourami...) 
I have plants growing like crazy in my water and the only thing I cannot seem to get to thrive is Java Fern and Amazon Swords (which should both be very hardy and fine in hard water....)    whether this is related to the hardness or not I can't say but I have essentially just given up on these two plants and found plenty which are doing great.


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## Paulus (18 May 2021)

Here still thinking if i should/want to use and buy a RO unit.
Currently using rain water as a test to see if it works good(just for the plants etc).
Also running CO2, plant ferts, high light etc.
What i noticed was that plants like rotala green did better compared like before.

Tap water here has (via water company site):
dH: *8,67 - 10,71*
pH: *7,75 - 7,89*

So for now, yes it works great but i am  depending on the weather/rain. Also it works because, well, we had more rain compared to the last 3 years  
But during the summer.......... The rain barrel will be more empty than full i am afraid.
Also using a 200L barrel on the attic which i have filled with rain water for use now (great fun to get it to the attic with jerrycans.......).
But also as a test to see if i will get/use a RO unit (which will be located on the attic) how it will work with a hose/tube back to the aquarium 2 floors down.
This test works. Simple 15/18 (more flexible) tube with a eheim tap on the end. gravity will do the rest.

Downside with use of a RO unit will be the water waste (and extra security needs to build in to prevent overflows etc. Dont want a 2 floor waterfall in my house..... )
So i am still doubting if i really need it for a high tech aquarium (current aquarium will soon be replaced/upgraded with an ADA 120P)
Looking at the aquariums like green aqua etc is using with TDS ratings around 120ppm is nice. But still........ Do i need to through away "waste water" for this...........


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## MichaelJ (18 May 2021)

Hello,
Not speaking of breeding (which is a whole different matter for many speices), there seem to be enough testimonials based on practical experience to at least make it plausible to suggest that fish that are naturally adapted to soft water will do better in soft(er) water rather than hard(er) water and vise-versa.  And personally I do believe in that, but where is the scientific evidence either way?  What are the limits and consequences in terms of metabolism/growth, coloration, physical / psychological stress, life expectancy, susceptibility to illnesses, mortality rate over time etc.?  Can my Cardinals or Rams be just as happy along those metrics at 25 KH/GH as they are at the current 5-6 KH/GH (assuming maintenance is impeccable in both cases) ? I doubt it, but I do listen when experts tell me otherwise.
Did anyone conduct scientific studies on this particular topic? Considering the size of  the ornamental fish trade and the number of people involved in this, I would think so, but I haven't been able to find any studies that just looked at water hardness in isolation.  I think it's rather consequential considering how much time and money hobbyists spend on potions and gadgetry to reach that certain KH/GH  and of course the well-being of our fish.

Cheers,
Michael


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## Nick potts (18 May 2021)

MichaelJ said:


> Hello,
> 
> Did anyone conduct scientific studies on this particular topic? Considering the size of  the ornamental fish trade and the number of people involved in this, I would think so, but I haven't been able to find any studies that just looked at water hardness in isolation.  I think it's rather consequential considering how much time and money hobbyists spend on potions and gadgetry to reach that certain KH/GH  and of course the well-being of our fish.
> 
> ...



You'll be hard-pressed to find a good scientific study on this or much else hobby related really.

While fish keeping is a popular hobby, studies etc cost money which just isn't there or just the fact that's it not all that important. Most of the scientific research in this sort of area takes place in commercial aquaculture and occasionally benefits us.


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## MichaelJ (18 May 2021)

Nick potts said:


> You'll be hard-pressed to find a good scientific study on this or much else hobby related really.
> 
> While fish keeping is a popular hobby, studies etc cost money which just isn't there or just the fact that's it not all that important. Most of the scientific research in this sort of area takes place in commercial aquaculture and occasionally benefits us.


@Nick potts  True. Pretty much all the literature I have been able to dig up on online science journals are related to commercial fish farming for food production.


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## Tim Harrison (18 May 2021)

Maybe try this as a possible line of further enquiry...

*Toxicological perspective on the osmoregulation and ionoregulation physiology of major ions by freshwater animals: Teleost fish, crustacea, aquatic insects, and Mollusca*​https://setac.onlinelibrary.wiley.com/doi/full/10.1002/etc.3676
https://setac.onlinelibrary.wiley.com/doi/full/10.1002/etc.3676
https://setac.onlinelibrary.wiley.com/doi/full/10.1002/etc.3676


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## MichaelJ (18 May 2021)

@Tim Harrison   Thanks for the link.

EDIT: I wish there would be a pop-up book version of this paper. I am pretty well versed in math and science in general being a computational imaging expert, but this is just too much jargon, biology and (organic) chemistry for me to grasp. I hope someone with a mind for this will read it and laymanize the conclusions pertaining to our discussion on water hardness.

Cheers,
Michael


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## Tim Harrison (19 May 2021)

The paper in itself is fairly tangential to what we're discussing.  I just thought osmoregulation etc in fish living in aquatic environments with increasing ion concentration might be a line of enquiry that would yield some results that were perhaps more relevant. 

I think the paper is explaining how different taxa have similar physiological ways of coping with increasing salinity and ion concentration. Although the mechanisms aren't completely understood and neither are the toxic effects of certain anthropogenic ions not usually found in the corresponding aquatic habitats in such high concentrations.

But that was back in 2016, so there maybe recent papers that have a more definitive answer. Although they may also be somewhat tangential to our discussion we might be able to draw some relevant inferences from them.


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## Saman (19 May 2021)

I know a lot has been said but I just thought it might be useful to add my experience here. I changed from hard London tap water to RO and there was a marked improvement in fish health - no more unexplained deaths basically. I love soft water fish so it made sense for me. Plant wise I think better in tap - I’ve just switched a new tank over to RO from tap and the plants aren’t growing so well now.


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## MichaelJ (21 May 2021)

Saman said:


> I know a lot has been said but I just thought it might be useful to add my experience here. I changed from hard London tap water to RO and there was a marked improvement in fish health - no more unexplained deaths basically. I love soft water fish so it made sense for me.


I agree wholeheartedly! I've had the same experience, but I wish there would be hard science and not just anecdotal evidence such as my own and yours (and many others) to back or contradict this.


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