RO/DI issue & question

[bob]

Hi everyone,

I'm about to put together a new system and wanted to start off on the right foot. I'm making a new batch of water and found my TDS to be a bit higher than it usually is. Right now it's reading about 10, when previously it was 0-3. Is this too high for a mixed reef? What kind of tolerance do you all practice? I have the 200gal mix of ESV salt en route and don't want it to go to waste by using bad water.

Could you also help me figure out where my system is having problems? The system itself is quite old but the prefilters+DI cartridge are about 7 months old; the RO membrane tested @~98% rejection 7 months ago so I kept it. It's been producing near 0tds water since then. I only use about 10 gallons every week or two, so I don't make a ton of water. Here are the current readings:

TDS in (tap): 474
After 3 prefilters: 420
After RO: 16 (96.2% rejection)
After DI: 9

The resin hasn't noticeably changed colors either. Thanks for the help! (x-post from R2R to get some local input!)

[tomgl]

How old are your filters? I just replaced mine and TDS after the membrane are 3 and 0 after DI. I have two meters to make sure. Can you post pictures so we can see how the lines are run?

[Tlalok]

Not too familiar with the system but I had the same issue with mine at first and it was brand new, my issue was low psi. Mine does really good at 60psi and anything lower than 48 it comes out dirty ... did u check ur Psi???

Sent from my Nexus S 4G using Tapatalk

[tomgl]

I run mine at 80 PSI.

[bob]

hey tom, the prefilters+DI resin are about 7 months old. It's hard to judge the actual age of my RO membrane since I've had it for quite some time (~6 years...many of which were in storage NOT being used). When I was ordering new filters 7 months ago the RO membrane was giving ~98% rejection so I kept it; I've read that you shouldn't have to replace them until they get down to like 90-92% rejection.

The lines are run normally: hose --> 3 prefilters (5 Micron Sedimentary, 5 Micron Granular Activated Carbon, 1 Micron Coconut Carbon Block) --> RO membrane --> DI cartridge --> water storage

water pressure was low for a bit due to a kink in the hose....but I fixed that today, now it's back to how it normally is. Ran it for a good 30 minutes after fixing the kink and the TDS was still around 10. (no pressure meter because I'm a newb and I got this RO/DI unit ~6 years ago)

[tomgl]

Are you using an autoshut off?

[bob]

Are you using an autoshut off?

No I turn the hose on and off manually

[tomgl]

I'd have to question the membrane and the resins being done. I have never had resin last seven months.

[bigronbo]

mine naturally with no pump is 65PSI

[Tlalok]

i turn the knob as far as it goes and it reads 85 but on my rodi meter it goes up to 60 -64 up

[kentlighting]

Membranes go bad if they dry out. I also haven't had resin last more than a few months when I fill a 50 gallon drum it's usually half way burnt threw. Your colors might not be changing because it may not be color changing di


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[bob]

Membranes go bad if they dry out. I also haven't had resin last more than a few months when I fill a 50 gallon drum it's usually half way burnt threw. Your colors might not be changing because it may not be color changing di


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Yea I'm thinking it's the DI resin. I'm pretty sure the membrane was wet in storage, especially since it's been performing well for the past few months. Going to go flush the membrane and see if that helps.

Does anyone in town carry DI resin? Or have any spare to sell (only need one canister full)? I need to get this water made ASAP!

Also are all RO membranes the same size? If I get a replacement does it have to be from the same place I bought it?

And is 10tds too high for reef? Or should I just dump the water and wait for some 0tds goodness?

[Gsxr1000rider]

I don't know anyone who carries it in town, I know BRA has RO systems in stock so call them that would be my best guess as to anyone with DI.

I dont see 10ppm being bad for a reef at all. A matter of fact my father n law has been using his sink to fill his ato bucket for the past year and his tank is growing mad. I know he has been fighting a algae issue from what I believe to be the mixture of RO/di water and sink water but im no expert.

It's not what you think!!!

[kentlighting]

his tank is growing mad. i prefer happy tanks as opposed to mad tanks, personal preference i guess.


i believe Aquatic Empires has some in stock.

[bob]

i believe Aquatic Empires has some in stock.

...i was just there earlier this evening! thats life for ya

[Gsxr1000rider]

i prefer happy tanks as opposed to mad tanks, personal preference i guess.


i believe Aquatic Empires has some in stock.

Ok let me rephrase that, his tank is extremely extremely happy. That's what I ment by "mad"....

It's not what you think!!!

[RickMartin]

Membranes will go bad if not stored properly. Although if you are getting 96% rejection thats not too bad. Time to change the resins and might as well change the prefilters while you are at it. You can't depend on the color changing to tell you its exhausted. I want 0 tds out of my system

[tomgl]

I agree with Rick. Zero TDS is the goal for my tank. I change my filters yearly. Even if they look good the carbon blocks wear out. I setup a flush for the membrane and it has extended to life out to a few years. I can't say that for the kitchen RO that does not have a flush but my goal my goal in the kitchen is not zero so no big deal. Five months is about as far as I can go on DI resin. I'm running a dual just incase. Also the resin should be moist or damp all the time like it comes in the bag. As for color changing I see it as a warning but I don't trust it. I would rather test the water to be sure. I needed DI resin fast last year called around and AE had it. This was when they first opened and were setting up the water systems. I'd call first.

[Buckeye Field Supply]

If you're getting 10 pppm our of the DI it was exhausted and needed to be replaced some time ago...

Folks don't forget - you should be sanitizing your RO or RODI system at least once a year.

Russ

[tugboat]

Yea I'm thinking it's the DI resin. I'm pretty sure the membrane was wet in storage, especially since it's been performing well for the past few months. Going to go flush the membrane and see if that helps.

Does anyone in town carry DI resin? Or have any spare to sell (only need one canister full)? I need to get this water made ASAP!

Also are all RO membranes the same size? If I get a replacement does it have to be from the same place I bought it?

And is 10tds too high for reef? Or should I just dump the water and wait for some 0tds goodness?

I just picked up sediment/carbon pre-filter and BRS DI Resin from BRA just yesterday.