Tapwater, RO, HMA, wet/dry and plants
- Thread starter IanB
- Start date
Hi,
:wb::wb::wb::wb::lol::lol:
It will have Bob as this is the water post sedimant and carbon filtration which doesn't remove everything but will have a lower TDS than your supply. Its unlikely that the contaminants that are flushed from the membrane will raise the TDS significantly above that which is fed into the membrane when you are flushing so regularly. This can be easily proven by comparing TDS readings pre and post membrane when the flush valve is open. The purpose of the flush valve is purely to stop the tiny pores in the membrane from fouling thereby keeping the membrane working efficiently.
I really wish you'd post up actual TDS values for discussion / comparison of all 4 main filtration stages. It really would help to get a handle on things.
I've just completed fitting brand new filters and retested my TDS values which are:-
Source water= 353ppm
pre membrane= 328ppm
Reject water= 448ppm
product water= 12ppm
The math model previously detailed fits perfectly as an explanation as to whats going on. 328+328/3+12=449 again allowances have to be made for accuracy of kit.
So by changing my pre filters it has improved slightly the efficiency of the system but my reject water TDS is still significantly higher than the source water. Next time I buy new carbon filters I'm going to opt for better ones and see how that affects things.
Chris.
:wb::wb::wb::wb::lol::lol:
It will have Bob as this is the water post sedimant and carbon filtration which doesn't remove everything but will have a lower TDS than your supply. Its unlikely that the contaminants that are flushed from the membrane will raise the TDS significantly above that which is fed into the membrane when you are flushing so regularly. This can be easily proven by comparing TDS readings pre and post membrane when the flush valve is open. The purpose of the flush valve is purely to stop the tiny pores in the membrane from fouling thereby keeping the membrane working efficiently.
I really wish you'd post up actual TDS values for discussion / comparison of all 4 main filtration stages. It really would help to get a handle on things.
I've just completed fitting brand new filters and retested my TDS values which are:-
Source water= 353ppm
pre membrane= 328ppm
Reject water= 448ppm
product water= 12ppm
The math model previously detailed fits perfectly as an explanation as to whats going on. 328+328/3+12=449 again allowances have to be made for accuracy of kit.
So by changing my pre filters it has improved slightly the efficiency of the system but my reject water TDS is still significantly higher than the source water. Next time I buy new carbon filters I'm going to opt for better ones and see how that affects things.
Chris.
Hi,
A useful link with a handy %rejection calculator and explanation which will help determine the condition of your membrane.
http://www.apswater.com/calcs.asp?Feed_conductivity=338&Product_conductivity=14
Chris.
A useful link with a handy %rejection calculator and explanation which will help determine the condition of your membrane.
http://www.apswater.com/calcs.asp?Feed_conductivity=338&Product_conductivity=14
Chris.
Unit is running now.. only produced a couple of litres of RO so it's all very new.. copious amounts of reject water for not much RO... waste pipe is jetting out, is that right?
TDS readings are..
Tap 387
RO 'waste' 384
Tank 429
TDS readings are..
Tap 387
RO 'waste' 384
Tank 429
Yes you will get a ratio of 3 or 5 to 1
A pump will reduce it
http://www.ebay.co.uk/itm/150398351858?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Our water pressure seems pretty good.. if I have the tap on full, the jet out of the waste pipe is ridiculous..
And it looks like I have a small leak somewhere in the RO unit.. can't see where from though..
And it looks like I have a small leak somewhere in the RO unit.. can't see where from though..
Is that even possible?
All the pipes are as it arrived and there's only 1 (white) in from the water supply and 2 (one red (waste) and one blue (RO)) out.. in what way could it be wrong as long as the white pipe is connected to the supply?
All the pipes are as it arrived and there's only 1 (white) in from the water supply and 2 (one red (waste) and one blue (RO)) out.. in what way could it be wrong as long as the white pipe is connected to the supply?
And the leak is from the back of the fitting above that tap.. I can stop it (the leak) by turning it down..
Should I be measuring RO output to determine how to set that tap?
Should I be measuring RO output to determine how to set that tap?
Hi,
Ian this is perfectly normal and means you have a reject ratio of 3.3:1.
You can reduce the overall reject ratio by adding more membranes. Upto 3 per system can be installed in series (i.e. the reject of the first is fed into the second and so on) and if you do have all 3 membranes installed then the reject to product ratio can fall to a ratio as low as 1:1. Some units run with higher reject ratio's than 3:1 and this depends largely on the quality of the source water.
The copious amounts of reject water wasted is the biggest disadvantage of RO filtration, especially for those on water meters. Waters unit charge is per square meter, which is 1000 litres, and is currently around £2 per unit. Therefore in your system you'll get about 230 litres of pure RO water per 1000 litres that your billed for if on a meter. Most LFS charge £2-3 to fill a 25litre barrel. So it is still cost effective to run your own unit.
Your unit shouldn't be leaking at all though and I'd advice finding the source of the leak and rectifying a.s.a.p. Sometimes if the push fit connectors aren't pushed fully home it can do this and at others a bit of PTFE tape applied to the threads of a screw in connector can sort it.
Its also check worth checking that the pipe entering a leaking push fit connector is cut at 90 degrees as it can cause problems sometimes if its not.
Chris.
Ian this is perfectly normal and means you have a reject ratio of 3.3:1.
You can reduce the overall reject ratio by adding more membranes. Upto 3 per system can be installed in series (i.e. the reject of the first is fed into the second and so on) and if you do have all 3 membranes installed then the reject to product ratio can fall to a ratio as low as 1:1. Some units run with higher reject ratio's than 3:1 and this depends largely on the quality of the source water.
The copious amounts of reject water wasted is the biggest disadvantage of RO filtration, especially for those on water meters. Waters unit charge is per square meter, which is 1000 litres, and is currently around £2 per unit. Therefore in your system you'll get about 230 litres of pure RO water per 1000 litres that your billed for if on a meter. Most LFS charge £2-3 to fill a 25litre barrel. So it is still cost effective to run your own unit.
Your unit shouldn't be leaking at all though and I'd advice finding the source of the leak and rectifying a.s.a.p. Sometimes if the push fit connectors aren't pushed fully home it can do this and at others a bit of PTFE tape applied to the threads of a screw in connector can sort it.
Its also check worth checking that the pipe entering a leaking push fit connector is cut at 90 degrees as it can cause problems sometimes if its not.
Chris.
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Hi,
Not necessarily.
The flow restrictor is what determines how much water is wasted not the system pressure once you have over 40psi, which most domestic dwellings will have. If your installation is lower than 40psi then a pump will help the system to run more efficiently but its not always a requirement.
Increasing the system pressure, which is what the pump is for (not the rate of flow) will increase the rate that product water is produced. A membrane is at its most efficient at a pressure of around 80-120psi which is what the pumps are usually designed to run at. The reject ratio in systems over 40psi will remain the same as in higher pressured system as the reject ratio is directly governed by the flow restristor.
Chris.
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Cheers Chris..
I done a little messing with the pipe and stuff and the leak seems to have stopped..
Just TDS checked the RO too and it came out at 13ppm..
I'm a bit loathe to start pulling pipes off at the mo, to check one of the stages, but I will get round to it (probably when I change the filter cartridges in a week or so)..
At its current rate, it'll take about 3hours 20mins to do 25 litres.. this is too fast isn't it?
The unit is rated at 120litres (50 US gallons) a day...
Do I need to slow it down?
I done a little messing with the pipe and stuff and the leak seems to have stopped..
Just TDS checked the RO too and it came out at 13ppm..
I'm a bit loathe to start pulling pipes off at the mo, to check one of the stages, but I will get round to it (probably when I change the filter cartridges in a week or so)..
At its current rate, it'll take about 3hours 20mins to do 25 litres.. this is too fast isn't it?
The unit is rated at 120litres (50 US gallons) a day...
Do I need to slow it down?
Hi Ian,
I see what you mean about the production rate but personally I wouldn't worry about it at all and actually take it as a bit of a bonus. Your TDS of 13ppm post membrane is about as good as you'll get and can be further improved by having a De-ionization stage or DI for short.
There was a link that I posted with a calculator in it a few posts back and it explains in it why you'll not get much lower than that post membrane near the bottom of the page.
Does your unit have a pressure gauge? and if so what is it?
Judging from what you've told us and your production rate I believe you have quite a high system pressure. So there would be absolutely nothing to be gained by adding a booster pump to your system.
When they design these systems they have no way of knowing what pressure your source water is supplied at so they tend to rate these units at a nominal value of 80psi. If you have more pressure then you'll achieve higher production rates and less lower. In your instruction manual they probably detail the system pressure that they used to calculate the rating of the unit somewhere.
If I remember rightly they supplied this system without a flush valve. So as the membrane ages it will clog reducing its effectiveness. They may have this in mind when selling it to you as a 50gpd unit so its still producing the stated output as it ages. That's just supposition though.
No real need to post up the TDS values I'm clear in my own mind as to what's going on. But it could prove interesting as a point of discussion. But its Bob's TDS values that I'd really like to know as its with his unit that things don't seem to be stacking up so clearly. I'd really like to compare the effectiveness of his pre filtration to mine with a view on buying better filters in the future and what exactly you get for your money with these more expensive replacement filter cartridges.
You shouldn't need to change your filter cartridges that soon and they should be good for 6 months but this is determined by two factors. The quality of your source water and the amount of water you filter. Best just to monitor your product TDS and when this rises significantly its a fair indicator that the pre-filters are shot and need replacing.
Chris.
I see what you mean about the production rate but personally I wouldn't worry about it at all and actually take it as a bit of a bonus. Your TDS of 13ppm post membrane is about as good as you'll get and can be further improved by having a De-ionization stage or DI for short.
There was a link that I posted with a calculator in it a few posts back and it explains in it why you'll not get much lower than that post membrane near the bottom of the page.
Does your unit have a pressure gauge? and if so what is it?
Judging from what you've told us and your production rate I believe you have quite a high system pressure. So there would be absolutely nothing to be gained by adding a booster pump to your system.
When they design these systems they have no way of knowing what pressure your source water is supplied at so they tend to rate these units at a nominal value of 80psi. If you have more pressure then you'll achieve higher production rates and less lower. In your instruction manual they probably detail the system pressure that they used to calculate the rating of the unit somewhere.
If I remember rightly they supplied this system without a flush valve. So as the membrane ages it will clog reducing its effectiveness. They may have this in mind when selling it to you as a 50gpd unit so its still producing the stated output as it ages. That's just supposition though.
No real need to post up the TDS values I'm clear in my own mind as to what's going on. But it could prove interesting as a point of discussion. But its Bob's TDS values that I'd really like to know as its with his unit that things don't seem to be stacking up so clearly. I'd really like to compare the effectiveness of his pre filtration to mine with a view on buying better filters in the future and what exactly you get for your money with these more expensive replacement filter cartridges.
You shouldn't need to change your filter cartridges that soon and they should be good for 6 months but this is determined by two factors. The quality of your source water and the amount of water you filter. Best just to monitor your product TDS and when this rises significantly its a fair indicator that the pre-filters are shot and need replacing.
Chris.
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Hi Chris..
No pressure gauge on the filter, no.. might be interesting to put one in if it's not too much dollar.. but our water flows at a heck of a rate (best we've had in the last 6 or so houses)..
Anyhoo.. flush valve.. the seller is going to send me the gear to add this when I ring and order the spare filters this week. I'm also going to chat about the leak I had.. but I suppose that could be due to high pressure too??
It's all dry now so it seems that running the unit at the 'right' flow rate fixed it.. which is nice.
The filters cartridges I wanted to change after this first 200-ish gallons because the water is pretty crap by all accounts and I'm producing up to 100 litres a day until the tank water is acceptable for new inmates..
Either way, I've been promised a good deal on 2 sets so I may as well get them in readiness..
Bit of luck the tank will be devoid of fish this week so I'll be adding ammonia to keep the filter sweet.. and it's getting a complete re-scape due to procuring a couple of rather large lumps of bogwood..
That and RO production should keep me busy (and when I'm up to my t*ts in water I'll be wishing I'd bought a 200 gallon per day RO unit so I could half drain the thing, scape it and re-fill it on the same day)...
No pressure gauge on the filter, no.. might be interesting to put one in if it's not too much dollar.. but our water flows at a heck of a rate (best we've had in the last 6 or so houses)..
Anyhoo.. flush valve.. the seller is going to send me the gear to add this when I ring and order the spare filters this week. I'm also going to chat about the leak I had.. but I suppose that could be due to high pressure too??
It's all dry now so it seems that running the unit at the 'right' flow rate fixed it.. which is nice.
The filters cartridges I wanted to change after this first 200-ish gallons because the water is pretty crap by all accounts and I'm producing up to 100 litres a day until the tank water is acceptable for new inmates..
Either way, I've been promised a good deal on 2 sets so I may as well get them in readiness..
Bit of luck the tank will be devoid of fish this week so I'll be adding ammonia to keep the filter sweet.. and it's getting a complete re-scape due to procuring a couple of rather large lumps of bogwood..
That and RO production should keep me busy (and when I'm up to my t*ts in water I'll be wishing I'd bought a 200 gallon per day RO unit so I could half drain the thing, scape it and re-fill it on the same day)...
Hi Ian,
For your application i.e. the amount of RO you'll need on a regular basis, I would consider getting serious about water storage so its there when you need it.
What I have is a 50gallon loft tank which I picked up second hand for £25 and an auto shut off kit which cost my about £20.
http://www.ebay.co.uk/itm/Polytank-PT2000-36x24x23-Water-Storage-Tank-50-Gallon-/200644823945?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item2eb75d0b89
http://www.ebay.co.uk/itm/AUTO-SHUT-OFF-KIT-AQUARIUM-RO-FILTER-WINDOW-CLEANING-/300389974646?pt=UK_Pet_Supplies_Fish&hash=item45f0a34276
Obviously I gave the tank a good clean but even new these tanks are quite reasonably priced and I have fitted mine with a john guest 22mm quick fit bulkhead connector and stopcock.
My current project is to install this in the loft (along with my RO filter) so I can utilize the head height of the house to aid water changes but its a work in progress at the moment fraught with potential problems that I'm sifting through bit by bit. I never seem to get enough spare time to sort things out the way I want them. So at the moment its in the garage and I decant into barrels and use as and where required. But it will be in the loft before the winter gets here. That's the plan anyway.
Chris.
For your application i.e. the amount of RO you'll need on a regular basis, I would consider getting serious about water storage so its there when you need it.
What I have is a 50gallon loft tank which I picked up second hand for £25 and an auto shut off kit which cost my about £20.
http://www.ebay.co.uk/itm/Polytank-PT2000-36x24x23-Water-Storage-Tank-50-Gallon-/200644823945?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item2eb75d0b89
http://www.ebay.co.uk/itm/AUTO-SHUT-OFF-KIT-AQUARIUM-RO-FILTER-WINDOW-CLEANING-/300389974646?pt=UK_Pet_Supplies_Fish&hash=item45f0a34276
Obviously I gave the tank a good clean but even new these tanks are quite reasonably priced and I have fitted mine with a john guest 22mm quick fit bulkhead connector and stopcock.
My current project is to install this in the loft (along with my RO filter) so I can utilize the head height of the house to aid water changes but its a work in progress at the moment fraught with potential problems that I'm sifting through bit by bit. I never seem to get enough spare time to sort things out the way I want them. So at the moment its in the garage and I decant into barrels and use as and where required. But it will be in the loft before the winter gets here. That's the plan anyway.
Chris.
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My problem would be where to store a 50 gallon tank.. it's possible it would fit in the shed (outside loo) where the RO is currently but I'd have to get my landlady to agree to the removal of the loo in there (the cistern leaks badly and everything.. it's totally unusable in its current state - but it is clean (and provides an awesome waste water facility))..
Which would be very convenient since that (brick built) shed
a) has a decent water supply and
b) is attached to the (also brick built) shed that will (hopefully) become a fish room next year..
Definitely something to think about.. be next year now though.. Hell Season is almost upon us..
Which would be very convenient since that (brick built) shed
a) has a decent water supply and
b) is attached to the (also brick built) shed that will (hopefully) become a fish room next year..
Definitely something to think about.. be next year now though.. Hell Season is almost upon us..