Ro Units

[Zante]

I have a 50gpd unit I bought in December, but since setting up the 400litre aquarium I upgraded to a 125gpd unit. Now I'm using both, the 125 at work where the big tank is, and the 50 unit at home where the other tanks are.

Recently I mistreated the 50 unit so I had to buy a new membrane, so I thought I'd buy a new set of filters too.

Now this unit is producing A LOT more water than before. I did a few calculations and now it is actually producing 50gpd. I got myself a TDS meter and it measures 20ppm from a tap water of about 380ppm.

The 125 unit at the moment is struggling to produce 25 litres in an 8 hour working day, and the water it produces measures at about 70ppm (haven't measured tap water there). It still has the membrane and filters it came with.

Both units run off a booster pump, and I regularly "wash" the membranes.

I was wondering... Do these units come with crap membranes? The 50 unit is a TMC and the 125 is a D-D, so it's not rubbish brands. I was wondering if it's worth buying new membrane and filters for the 125 unit...

Does anyone have a similar experience?

 

[ainsy]

If the flow is significantly reduced then your prefilters may be blocked. How regularly do you replace them?

 

[Zante]

The whole 125 unit is less than three months old.

 

[ainsy]

Have you tested the TDS of the incoming water at work?

If you have really poor quality incoming water (I do!) then your prefilters may need changing every 3 months (mine do!) I have had to add 2 extra prefilters 20micron and 10 micron - just so that I can get three months out of them.

It is possible that it is so dirty that the unit is working correctly & is only able to reduce it to 70. Have you calibrated the TDS meter? It is possible that it is out of whack if you haven't .

 

[Zante]

Have you tested the TDS of the incoming water at work?

If you have really poor quality incoming water (I do!) then your prefilters may need changing every 3 months (mine do!) I have had to add 2 extra prefilters 20micron and 10 micron - just so that I can get three months out of them.

It is possible that it is so dirty that the unit is working correctly & is only able to reduce it to 70. Have you calibrated the TDS meter? It is possible that it is out of whack if you haven't .

Nope, the tap water at work isn't tested, but I remember measuring hardness with a reagent jbl test and it was around 20gh. (if it's any help it's the Camden area in London). The tds meter is fine, new and calibrated. I'll get a reading tomorrow when I go and feed the fish at work and report back.

I must say I don't remember the 125 unit being particularly productive even when brand new, but I didn't pay much attention...

In the meantime I'll look into pre filters like you mentioned, if I should need them I'll know where to get them.

 

[Zante]

Just measured tap water at work: approx. 300ppm. The definitely is something wrong with my 125 unit...
First thing I'll try and dismantle it and put it back together, I wonder if it could just be that there's a filter or the membrane not properly installed.

 

[ainsy]

I would expect that if you start out at a TDS of 300 then the product should be in the region of 15-30.

May be worth checking if the membrane is correctly seated in the housing.

 

[Zante]

Yep, just checked, everything is installed ok.

It must be the filters that are buggered. I tried to get replacements yesterday, but the LFS had run out.

I'll have to make do with what I have for a few days. No big issue, I've been going like this for weeks now, one extra week will not kill me, also, 70ppm is still better than 300ppm even if it's that slow to get it out.