RO Waste

[Mark Grigg]

Ok I'm scratching my head here, I've fitted a new RO unit yesterday I knew there was a waste pipe however I wasn't really prepared for the amount of waste, the system has a regulator on the waste pipe which is shut off but allows a pin hole to remain open at all times, the only logic to me here is that this is to stop the system becoming over pressurised?

But why I ask isn't there a system you can keep plumbed in 24/7 and use as needed (for an auto top up in this instance) without having a constant loss of water.
I'm not a fan of wasting water, so this does grate on me somewhat so looking to see if I can improve this situation.

Mark.

 

[Andrew Butler]

Hi Mark,
It sounds like this is your first time producing your own RO water!
The best systems widely available will produce 1L of waste water for every 1L produced so in essence you only get 1L RO water from 2L of mains water.
A lot of systems will take 3L or more to make 1L of RO water.

 

[Edvet]

Improving the pressure over the membrane will increase yields and decrease loss, nut sure how this can be done in simple household systems. You can use the "waste"on 1) hard water fish ( middle america's), 2) pond, 3) garden plants 4) household water, just collect it

 

[Mark Grigg]

Improving the pressure over the membrane will increase yields and decrease loss, nut sure how this can be done in simple household systems. You can use the "waste"on 1) hard water fish ( middle america's), 2) pond, 3) garden plants 4) household water, just collect it

It appears not to be very efficient 1 litre of waste takes just over 3 minutes and 1 litre of clean around 8 minutes
So the waster will produce 38,000 gallons a years based on these figures, which is just not ethical.

 

[ian_m]

Any RO system running from simple cold water mains pressure, will typically produce a ratio of anywhere between 5 to 20 litres of waste water to 1 litre of RO water, even more when water is cold. Typically 5:1 on 3bar mains pressure.

The main way to improve the efficiency, maybe to even as low as 1:2 (RO to waste) is to increase the incoming pressure with a booster pump.

For example.
http://www.ro-man.com/shop/pumps/ro-man-intergrated-pump-box-for-ro-systems-50-100-gpd.html

There are other types available as well.

As for turning off the incoming water when storage tank is full you need one of these.
http://www.ro-man.com/shop/pumps/auto-shut-off-kit.html

Remember to either test or dechlorinate your RO water !!!! as RO units are not 100% guaranteed to remove chlorine and chloramine. This is the one case, in fish keeping, where a chlorine and ammonia test kits can be relied to give reliable results, as there will be no other contaminants in the RO water.

The reason for this is chlorine (and chloramine) MUST be removed by a suitable carbon pre-filter in the 1st stage as they can damage the RO membrane an appear in the RO water. However chloramine is more insidious as the carbon pre-filter will break it down to chlorine and ammonia. If the pre-filter is old or flow rate is too fast the ammonia (and to a certain extent chlorine) will not be absorbed by the pre-filter and appear as toxic levels in the final RO water. This is why I saw my local fish shop testing the RO water for chlorine and ammonia. The ammonia (and chlorine) will gas off in 24 hours. Though if you get a positive chlorine result your membrane is now ruined. So either keep track of pre-filter life or test RO water or just add Prime (to dechlorinate and remove ammonia).

 

[Mark Grigg]

Any RO system running from simple cold water mains pressure, will typically produce a ratio of anywhere between 5 to 20 litres of waste water to 1 litre of RO water, even more when water is cold. Typically 5:1 on 3bar mains pressure.

The main way to improve the efficiency, maybe to even as low as 1:2 (RO to waste) is to increase the incoming pressure with a booster pump.

For example.
http://www.ro-man.com/shop/pumps/ro-man-intergrated-pump-box-for-ro-systems-50-100-gpd.html

There are other types available as well.

As for turning off the incoming water when storage tank is full you need one of these.
http://www.ro-man.com/shop/pumps/auto-shut-off-kit.html

Remember to either test or dechlorinate your RO water !!!! as RO units are not 100% guaranteed to remove chlorine and chloramine. This is the one case, in fish keeping, where a chlorine and ammonia test kits can be relied to give reliable results, as there will be no other contaminants in the RO water.

The reason for this is chlorine (and chloramine) MUST be removed by a suitable carbon pre-filter in the 1st stage as they can damage the RO membrane an appear in the RO water. However chloramine is more insidious as the carbon pre-filter will break it down to chlorine and ammonia. If the pre-filter is old or flow rate is too fast the ammonia (and to a certain extent chlorine) will not be absorbed by the pre-filter and appear as toxic levels in the final RO water. This is why I saw my local fish shop testing the RO water for chlorine and ammonia. The ammonia (and chlorine) will gas off in 24 hours. Though if you get a positive chlorine result your membrane is now ruined. So either keep track of pre-filter life or test RO water or just add Prime (to dechlorinate and remove ammonia).

Many thanks Ian, I've just ordered an automatic shut off valve from RO Man, this will do the job perfectly. I'll test the water once I'm up and running.

 

[Danielm]

Depressing isn't it!

you can buy a simple in-line pressure gauge for a few quid - this will give you some indication of the pressure your system is running under. As other have said however a booster pump really is the way to go.

I can run 25 litres in roughly 2 hours (pumped) - prior to this, in the winter it would take more like 5 hours - (caveat that my unit lives in the garage, which is detached)

An alternative for your approach would be to house the RO in a separate container (i use a 25 litre drum that fits down the side of the tank and cannot be seen) and run it to the Sump via an ATU -

 

[ian_m]

I'm not a fan of wasting water, so this does grate on me somewhat so looking to see if I can improve this situation

My metered water costs £3.20 for 1000litres, 0.31p per litre. Thus at say 6:1 waste to RO works out 2.17p per litre. Doing 50% of my 180litre will cost £1.95 and for 52 weeks is £100 a year in water...Ouch.

 

[Mark Grigg]

My metered water costs £3.20 for 1000litres, 0.31p per litre. Thus at say 6:1 waste to RO works out 2.17p per litre. Doing 50% of my 180litre will cost £1.95 and for 52 weeks is £100 a year in water...Ouch.

I have 475 litres to deal with, I'm going to aim for a 13% water change per week, 63 litres at 9 litres per day. I'm thinking of sending the waste to the garden plants.

 

[Andrew Butler]

a booster pump really is the way to go

+1 but if you are putting it on a float valve you would need an auto shut off for the pump too as I know has been mentioned but have seen forgot.

I might suggest if you are keeping at a constant level using a float valve that you think about possibly replacing it from time to time and letting it drain from time to time to free up the mechanism as I have seen quite a few stories of them getting jammed open and making lots of mess - If you can go 1 better and put an overflow in the storage container which also goes to mains waste.

I'm going to aim for a 13% water change per week

I think most people on here will tell you 50% per week is good practice with planted tanks

 

[Fiske]

I think most people on here will tell you 50% per week is good practice with planted tanks

Depends. If using EI in a high tech tank, yeah. If going lowtech, dirted or similar you can make do with much less. Also bioload has something to say here.

 

[ian_m]

I have 475 litres to deal with, I'm going to aim for a 13% water change per week, 63 litres at 9 litres per day

I think most people on here will tell you 50% per week is good practice with planted tanks

Generally with high tech planted tanks ie high lights, CO2 and EI ferts, 50% water change per week is recommended, to prevent organics buildup (and to a lesser extent unused ferts).

However you must mix your RO water with tap water or GH booster as 100% soft water is in fact dangerous in a fish tank. This is because RO water has no buffering capacity and the slightest addition of acid (or alkali) will result in massive quick pH swings, generally called a pH crash, which can be fatal to your fish. So either say mix 50% RO with tap water (assuming the reason you are using RO is because your water is hard, if your water isn't hard, why are you using RO ???) or add GH booster. Both methods you should aim for 4-8dKH hardness.

 

[Mark Grigg]

+1 but if you are putting it on a float valve you would need an auto shut off for the pump too as I know has been mentioned but have seen forgot.

I might suggest if you are keeping at a constant level using a float valve that you think about possibly replacing it from time to time and letting it drain from time to time to free up the mechanism as I have seen quite a few stories of them getting jammed open and making lots of mess - If you can go 1 better and put an overflow in the storage container which also goes to mains waste.


I think most people on here will tell you 50% per week is good practice with planted tanks

I'm going to run a small pond pump from a timer, just need to work out how long to set the timer for. ref the boost pump I'll see how it goes first.

 

[Daneland]

My metered water costs £3.20 for 1000litres, 0.31p per litre. Thus at say 6:1 waste to RO works out 2.17p per litre. Doing 50% of my 180litre will cost £1.95 and for 52 weeks is £100 a year in water...Ouch.

My local shop charges £3.50 for 25 liters, if I do only 20% WC (25 lt) weekly I pay £182. I hate it. TDS of tap water is around 400.

 

[dw1305]

Hi all,
It also depends upon the amount of ions in your tap water, the more ions you have the greater the amount of waste water. To get the maximum yield you need soft water, a warmed supply and a booster pump.

I'm not saying it is an alternative for every-body, but rain-water is free and freely available. If you had enough storage you could have collected many 1000's of litres of rain-water over the last month off an average roof.

cheers Darrel

 

[Andrew Butler]

Generally with high tech planted tanks ie high lights, CO2 and EI ferts, 50% water change per week is recommended, to prevent organics buildup (and to a lesser extent unused ferts).

I'm pretty sure Mark is using CO2

why are you using RO ?

I think this is a good question! I just wonder if Marks experience is from a marine background where you need to use RO to top up. (not for water changes)

I'm going to run a small pond pump from a timer, just need to work out how long to set the timer for. ref the boost pump I'll see how it goes first.

Just remember the productivity of your unit can vary from day to day.
If you look at Ians previous comment adding the booster pump should improve the efficiency of your unit which I think is a big concern of yours.

The main way to improve the efficiency, maybe to even as low as 1:2 (RO to waste) is to increase the incoming pressure with a booster pump.

 

[Zeus.]

Lucky for me at work I have no water meter but I do use a booster pump and have a deionizing resin filter too. Need pure water at work as machines won't work if TDS is above 40. Have a backup distiller too. Having issues with the RO unit as it happens ATM have replaced the booster pump was 7 years old need some new values also which I have ordered of e bay.

 

[Mark Grigg]

Hi all,
It also depends upon the amount of ions in your tap water, the more ions you have the greater the amount of waste water. To get the maximum yield you need soft water, a warmed supply and a booster pump.

I'm not saying it is an alternative for every-body, but rain-water is free and freely available. If you had enough storage you could have collected many 1000's of litres of rain-water over the last month off an average roof.

cheers Darrel

I do have 400 litres already stored which we don't use.

 

[Mark Grigg]

I'm pretty sure Mark is using CO2


I think this is a good question! I just wonder if Marks experience is from a marine background where you need to use RO to top up. (not for water changes)


Just remember the productivity of your unit can vary from day to day.
If you look at Ians previous comment adding the booster pump should improve the efficiency of your unit which I think is a big concern of yours.

I will be using CO2 for sure, as for the RO I do have more fish experience than plants which has covered virtually every fish you can think of over the years, I like not to shock a system and thus the RO made sense doing small changes via an auto top up and adding nutrients back in daily for the plants. plus the removal of chlorine and especially chloramine was a concern. I'm in a soft water area with neutral Ph.

I'll hold off the booster pump for now, the efficiency isn't great as mentioned, however it was the continuous waste when the float valve was closed which concerned me most, so with the auto shut off valve from RO Man, this will reduce the waste tremendously.

 

[ian_m]

If you have soft water why are you using RO ? Many people would die to have soft water where you can harden it up to your requirements (4-8dKH). My water is very hard, having come from a chalk aquifer and plants grow monstrously, fish reproduce like rabbits with what comes out my tap.

If going high tech, you will need at least 50% weekly water changes to remove waste organics. If left the organics build up quickly and algae quickly follows. If I miss a water change it is pretty obvious due to BBA appearing as well as green spot algae within a couple of days.