Ro Unit

[Jimyfloyd]

Hi there I have this RO unit:

http/www.ro-man.com/shop/product_info.ph...c6e9ead5b8e25f4

I just got a TDS meter and the water going in reads at around 300 and the water out is still at 25. The unit is about 4 months old now.

If some of you have seen my journal you will note I've had a problem with cyano and still do. Could the 25ppm be the problem?

If so how do i reduce this.

My water pressure is low and the unit has no pump but I don't think that affects the output quality jsut the quantity?

Thanks in advance.

James

 

[seffieuk]

Get yourself a DI unit

http/www.ro-man.com/shop/product_info.ph...8af82c33332512e

I've just done the same, haven't fitted mine yet as it only came a couple of days ago

Seffie x

 

[rabbut]

Hi,

I assume you have flushed the membrane, and send the first 1/2 hours output to waste before collecting your sample for testing? For the first few minutes, RO units kick out water of a higher TDS than usual, due to TDS hammering in the membrane, basically where solids have moved across the membrane to the use side in the absence of pressure while the unit is switched off If this is the case, you may be in need of a new membrane as well as potentially a DI like Seffie suggests. A properly functioning membrane would produce RO of no more than about 3ppm after the first 1/2 hour to settle down I'd be supprised if the membrane has gone already though, as RO man make some of the best available. I assume you store the membrane wet (don't let all the water drain out after use)?

HTH
Rabbut

 

[Jimyfloyd]

yeh i always flush it before use.

Odd i shall run it again now and see what i get, try the DI unit and if not new membrane i guess!

When you say wet - i switch it off and it's usually left a few days and i'll flush and make soem more...

 

[rabbut]

If the water can drain away from the membrane when you allow it to sit, it will be killing your membrane. If the water cannot drain out of the unit, it will not be doing any harm. I suggest either fitting a valve to the use, waste and input ideally, and closing the use, then waste, then feed valves before shutting of water supply to the unit, or cutting off supply with the unit below the pipe ends for each of feed, use and waste

The first half hours water from the use will be scrap when you turn the unit on again due to TDS hammering, so make sure you are only taking TDS readings and start collecting your water after allowing the unit half an hour of normal running to sort itself out

If the TDS is too high out of the membrane after allowing the unit to clear, you will have to replace the membrane regardless of if you fit a DI unit anyway, as the membrane will be junk and not working correctly if you find that to be the case Also, the resin in the DI unit will last longer if you connect it up to the unit after it's had it's half-hour clearing time

All the best
Rabbut

 

[Jimyfloyd]

ok so I've tested it again.

Still coming out at 25ppm on the TDS meter. Before I go and buy a new membrane (this one is only 4 months old and hasn't had much use) what is the best wa to test the TDS is calibrated correctly. It came with a solution in a bag that tested at 0...

Would the 25ppm be the cause of my cyano problem?

 

[rabbut]

Quite probably. Definitely sounds like a knackered membrane may be at fault to me considering the TDS output of the unit

If the calibration fluid is a zero standard, and the TDS meter reads zero on it, your meter is calibrated correctly. It's best to have several fluids though, each with a different TDS, to ensure the meter is accurate over the range you are testing however

To get good membrane life, kake sure it is flushed after every use, before putting it into storage, and that it is always kept wet after it's first use. They ship with resin on them to keep them wet (hence why the first two hours output of a new membrane is all scrap, as you flush this resin off the memrane) and hence why they don't come in water. Without the resin on them though, they dry out and fail very quickly if not stored correctly

All the best
Rabbut

 

[seffieuk]

Cyano is more likely down to poor flow and /or overfeeding

Seffie x

 

[SkiFletch]

Either way a TDS reading that high indicates a membrane that needs flushing. Do you have a flush kit?

 

[Jimyfloyd]

Flow is high. Have 2 koralia 1's and a eheim canister pumping the tank. Feeding is low IMO. Maybe a frozen cube every other day.

I have a switch that i flick on the unit and it diverts all flow to the waste - i assume this is the flush.

I suspect you are correct rabbut and the membrane is knackered. I usually just close the water flow off and leave it liek that. I assumed that the water would stay in the unit until next use...is this incorrect?

 

[rabbut]

Depends on the output and waste lines and how they are relative to the unit. Hard to say without seeing the unit in-situe, but in many cases, water just staying in the unit isn't the case

 

[seffieuk]

Depends on the output and waste lines and how they are relative to the unit. Hard to say without seeing the unit in-situe, but in many cases, water just staying in the unit isn't the case

you have me worried now - my unit sits under the sink and I keep the pipes on top by the sink - I had assumed the same thing, that when I switched it off some water would stay on the membrane as the pipes are higher than the unit

Oh heck............. I have just bought a DI in the hope of getting down to 0 TDS

Seffie x

 

[rabbut]

The DI will pull the TDS down more, but the output of the unit without DI should be 1/100th of the TDS of the input water or less. If you have 300 TDS from the source, the use should be <3, for 500 source, <5 for the use e.t.c If not, the membrane needs flushing. If this does not get the TDS back down, you need a new membrane

If the pipes are all going up-hill after the unit, you should still have a wet membrane in there, it's if any of them go down that you get issues with the membrane drying up...

All the best
Rabbut

 

[seffieuk]

When you say 'all' do you mean the waste and the ro water pipe or every pipe, even the ones under the sink?

Ok, this is going to sound really stupid when you say flush (i don't have an in-line one on my unit) is that just running water through it or is it something else?

Seffie x



ps think I need a new membrane if it should be <5

pps why the hell don't they tell you these things when you buy and install the thing

 

[rabbut]

Lol, that would be spoon feeding you information. They'd rather you found out the hard way, cause then you have to buy a new membrane off them

By all pipes, I mean the feed, use and waste pipes all need to go up-hill away from the unit, or the unit will be able to drain and hence the membrane can then dry up.

My understanding of how flush kits work is that they use equal pressure on each side of the membrane to push any residue off of it, hence reducing how badly its clogged up Having never actually used a unit with a flush kit though (I've only used units without flush kits installed) I've never plumbed on in and hence cannot say for certain No Doubt Ski will be back a some point to shed some light on the subject

All the best
Rabbut