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#1
GiantBen

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I've been having a bit of a cyanp problem in my new tank. My understanding is that this is almost certainly due to excess phosphates? I have tested fresh mixed salt water and got a 0 reading. My TDS meter reads zero all the time. Is there anything else I should be testing to make sure my RO/DI is as good as possible? Thanks.

#2
solefald

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There is no way in hell freshly mixed salt water would be 0 TDS. Salt mix adds TDS by definition. There is no point in measuring salt water for TDS. You need to be measuring your RO/DI

Your meter is broken. Just test your tap water. If meter still shows 0, throw it away.

Edited by solefald, 21 March 2012 - 02:42 PM.


#3
Deckoz2302

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he means 0 phosphates from the salt. and 0 tds on the ro/di output

Ben its a phase...it will pass...get some diversity of macro and more corals to suck up the nitrates & phosphates.

Edited by Deckoz2302, 21 March 2012 - 02:53 PM.


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#4
GiantBen

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he means 0 phosphates from the salt. and 0 tds on the ro/di output

Yes, this. Sorry.

#5
iball1804

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Your meter is broken. Just test your tap water. If meter still shows 0, throw it away.

Well... there's a chance he's got 0 TDS in his tap water, it's just highly unlikely.

Incorrect assumptions lead to death. Trust me.

#6
GiantBen

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Incorrect assumptions lead to death. Trust me.


:huh:


soooo.....any suggestions?

#7
henningero

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Along with the other suggestions, try keeping your lights off few a few days. After that, keep the lighting reduced for a while until the water params are better. That worked in the past for my Cyano problem.

#8
GiantBen

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Sorry, I meant any suggestions in other things to test in the RO.

#9
AZDesertRat

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You cannot accurately test contaminants in RO, RO/DI or ultrapure water due to its agressive nature.

You need a TDS meter and the RO TDS should be somewhere around 96-98% less than the tap water TDS was to begin with. The RO/DI should be 0 TDS if it is working properly. Phosphate test kits and the like are not accurate with RO or RO/DI water.

Have you checked with your water utility to see if they do any treatment for corrosion control in the distribution system? Many utilities feed phosphates as a form of treatment and without very good DI you may not be capturing it all. You may need better resin or if you have a horizontal DI you may need a full size vertcal 20 oz DI for better contact time.

Are you using a handheld TDS meter or is it an inline? What are your tap water, RO only and RO/DI TDS readings?
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#10
GiantBen

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I'm using a spectrapure system. MaxPlus or something. I've had it for a couple years. Never replaced the membrane. I have replaced the pre-filter sediment cartridges. Last time I replaced the filters (a month ago), I only replaced the silica buster because the Spectrapure guy said I probably didn't need to be replacing the pre-filters every 6 mo. He said the membrane and pre-filters only need replacing when the flow is substantially reduced through the unit.

Questions:
(1) Is this accurate or should I be replacing all the cartridges at once?
(2) Should I have replaced the membrane?
(3) I didn't bleach the chambers last time, so this could be part of the problem. Yes?
(4) I *should* be able to test freshly mixed salt water for phosphates right?
-If not, why not?

Thanks.

#11
AZDesertRat

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The 6 month rule is an acceptable guideline in most cases. It is very easy to write the date on the unit or bracket and remember to do it all over again 6 months later, if anything it is better to err on the safe side.

If you have very good tap water conditions and don't mind some extra work on your part you can go longer than 6 months but you need to monitor both headloss or pressure drop at the RO membrane due to filter plugging or fouling and for the presence of chlorine in the treated water when the carbon begins to exhaust. It usually is best to have an additional pressure gauge on the tap water side of the sediment filter so you can compare it to the gauge on the RO housing at a glance for head loss and to have a low range chlorine test kit and use it.

This requires more work but it can save you a little money on replacements as long as you watch things closely. Its when you neglect to monitor things though and the headloss starts to affect RO membrane performance causing shorter DI life or chlorine gets to the RO membrane and damages it wher it actually ends up costing more. For most the 6 month rule works out best. It is also easyto disinfect the system while you have it down for replacements so another reason to do so.

It only takes a few psi pressure drop to start lowering the rejection rate so I like to keep clean fresh filters in place to keep the removal efficieny up and DI life long. Resin is as or more expensive than replacement filters.

The only ways to know when the RO membrane needs replacing is with your TDS meter and by watching your GPD. When the rejection rate starts dropping below say 95-96%, DI life is cut in half or more so requires more frequent replacement and drives the cost of operation up. Also when a membrane starts failing it may show up as reduced GPD or production rate as the membrane surface starts plugging.
My experience has been as long as you use the same high quality replacement filters Spectrapure provides, ie a 0.5 micron absolute rated sediment filter and a 0.5 micron 20,000 gallon carbon block, the membrane should last 5+ years and some users are seeing as long as 10 years of heavy use. Monitor your TDS and calculate your rejection rate every month or two and keep track or trend it over time. What are all four of your TDS readings on the two meters? What is your incoming or static water pressure? What is the pressure when the system is in operation? What is your water temperature and what is your exact measured waste ratio today? These things all aid in troubleshooting a system.

This is a good template they have on their site that walks you through testing your system.
http://www.spectrapu...ALC-FORMULA.pdf

Yes you can test phosphates in saltwater, just not in pure water with hobbyist type kits and meters.
16G Bowfront Nanoreef. 100G SPS dominated reef.

#12
Whys

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After 2 years, you probably want to replace the RO membrane. How long they last depends on your tap water, and if it's fairly clean then 2 years for an RO membrane isn't ridiculous, it's just probably time to replace it.

I wouldn't worry about the prefilters much. Your understanding is correct. They only need replacing if they become clogged. However, you'll probably want to replace your carbon block cartridge at least once a year.

I've never disinfected my RO unit. They are designed to kill everything before it comes out the spout. That is a part of their function. However, any chlorine added to the water by your municipality is also removed, thus any nutrients in the water can lead to bacterial growth if stored for any length of time.

If your RO/DI reads 1, that's perfectly okay.

I find it useful to use both an inline TDS meter as well as a hand held to double check the inline's calibration every now and then.

Hope this helps. :)

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#13
AZDesertRat

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There is absolutely no reason to replace a RO membrane if the rejection rate and production rate are still where they should be. Why would you waste money like that?

How long they last is more a function of the quality and maintanance of your sediment and carbon block filters and even more importantly how well you adhere to the 4:1 waste ratio to ensure it is well flushed. Those two along with using softened water makes a membrane last for many many years with little reduction in performance. Every major membrane manufacturer recommends softened water.

The reason for disinfecting a RO or RO/DI system is to reduce the likelyhood of virus or bacterial growth inside the housings and is a necessary piece of maintanance. You are providing the perfect environment for growth with nice slow water flow, the absence of chlorine since you have removed it with the carbon block warm or at least room temperature so no extremes etc. The sediment and carbon filters do not kill or remove any bacteria or virus present so it could and does live inside the housings. I have personally seen people hospitalized on more than one occasion due to improper or no filter system maintanance amd it is not a pretty sight, especially if they are older or have a weakened immune system. It happens more often than you might imagine.

A RO/DI reaing of 1 means your DI resin is exhausting and releasing weakly ionized substances back into the treated water. some of the weakly ionized substances include nitrates, phosphates and silicates, all of which may not register well on a hobbyist grade TDS meter so you may have higher levels than you realize. When you fisrt start to see TDS in the finished water start loking for replacement DI soon. In the case of your MaxCap system, you need to watch both the MaxCap and the SilicaBuster TDS readings as a bad MaxCap will soon eat a SilicaBuster cartridge.
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#14
Whys

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All good information. My point was intended as a typical scenario for reef water, not drinking water. For reef water, I've never had the need to disinfect my RO/DI. But perhaps that is folly of me?

Also, to clarify, a reading of 1 doesn't necessarily mean your DI resin is exhausting. A reading that rises from 0 to 2 is a good sign of that, while a reading of 1 could mean just about anything. That's all I'm trying to say.

Again, all good information.

Also of note, too much water pressure will blow out an RO membrane. At 82 psi, I learned the hard way. :]

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#15
C.I._Reefer

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All good information. My point was intended as a typical scenario for reef water, not drinking water. For reef water, I've never had the need to disinfect my RO/DI. But perhaps that is folly of me?

Also, to clarify, a reading of 1 doesn't necessarily mean your DI resin is exhausting. A reading that rises from 0 to 2 is a good sign of that, while a reading of 1 could mean just about anything. That's all I'm trying to say.

Again, all good information.

Also of note, too much water pressure will blow out an RO membrane. At 82 psi, I learned the hard way. :]


wow, 82 PSI shouldnt blow out a membrane though. I think it must have been defective.

#16
Whys

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wow, 82 PSI shouldnt blow out a membrane though. I think it must have been defective.


I had it hooked directly to an auto top off, which by itself should haven't been a big deal, but something about the check valve I think was creating huge back pressure whenever the ATO would click on and off. The thing would ping and rattle like a rifle ricochet as the pressure gauge needle jumped from zero to 90 to zero again. It put up with it for a few days. :]

I use a pressure reducer now. At 45 psi and no check valve, there's no ping, no ricochet, no problem.

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#17
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I had it hooked directly to an auto top off, which by itself should haven't been a big deal, but something about the check valve I think was creating huge back pressure whenever the ATO would click on and off. The thing would ping and rattle like a rifle ricochet as the pressure gauge needle jumped from zero to 90 to zero again. It put up with it for a few days. :]

I use a pressure reducer now. At 45 psi and no check valve, there's no ping, no ricochet, no problem.


Wish i had that problem. Mine is exactly the opposite. I dont know my pressure, but based on some not so accurate math, it seems it is barely over 40 psi. I am lucky to be able to produce 35-40 gallons in a day with my 100 gpd membrane, and that it probably pushing it with water temps near 60 degrees.

Edited by C.I._Reefer, 22 March 2012 - 09:31 PM.


#18
solefald

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Wish i had that problem. Mine is exactly the opposite. I dont know my pressure, but based on some not so accurate math, it seems it is barely over 40 psi. I am lucky to be able to produce 35-40 gallons in a day with my 100 gpd membrane, and that it probably pushing it with water temps near 60 degrees.


I barely get 30-32 psi!

#19
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I barely get 30-32 psi!



do you still get an adequate production ratio? I was under the impression you would have problems producing water at all under 40 psi

#20
AZDesertRat

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40 psi is about the mimimum a membrane will function at with any level of efficiency and its not very good at that point. The Dow graphs only go down to 38 psi.

Membranes are tested at 150 psi so if you blew a membrane at 83 psi, it was not the membranes fault, it was other components as you stated. The weak links are the fittings and housings on many systems which may not be ANSI/NSF or UPC tested and certified for 125 psi working pressure. That means they will work at 125 psi all day long and are pressure tested to 3x that for a safety factor. Many off brand imported RO and RO/DI units use non approved components so are more likely to fail.

I run at 95-100 psi always and never had so much as a drip. Quality pays off.

There is absolutely no reason anyone should settle for any TDS reading with a properly functioning RO/DI system, even a TDS of 1 is unacceptable in my book. ANY system should be capable of 0 TDS, any. The difference in a good, mediocre and bad system is how long it stays at that 0 TDS and what it costs to keep it there. Again, quality pays off.

Any RO or RO/DI system should be disinfected regardless if its for aquarium use or human consumption. If you have never seen red slime algae inside a membrane housing you haven't lived yet! Its UGLY and smells like all get out. And it will plug a membrane pretty quickly. An annual or 6 month disinfection will help prevent this as wall as other bacterial and virus growth and is the smart thing to do. I may get lazy on some things but water quality is not one I mess around with since water is the single largest ingredient in my aquariums and its easy and inexpensive to provide the very best.
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#21
Whys

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I run at 95-100 psi always and never had so much as a drip. Quality pays off.


Now you have me wondering. Do you think it was the check valve and if so do you think I should increase my pressure up from 45 psi? It really was a quality membrane that I used without problem for 2 years. I think the problem was that it was getting something like 90 psi from one direction, then 90 psi from the other direction, and was doing that in rapid fire oscillation.

There is absolutely no reason anyone should settle for any TDS reading with a properly functioning RO/DI system, even a TDS of 1 is unacceptable in my book. ANY system should be capable of 0 TDS, any. The difference in a good, mediocre and bad system is how long it stays at that 0 TDS and what it costs to keep it there. Again, quality pays off.


It's not that I disagree here, it's that I don't consider a reading of 1 to be reliable for most TDS meters. It could just as easily be a dirty probe or calibration drift. This is why I think it's a good idea to have both an inline and handheld TDS meter. My handheld is slightly more sensitive and accurate. Sometimes what the inline calls 1 TDS, my handheld calls zero.

Any RO or RO/DI system should be disinfected regardless if its for aquarium use or human consumption. If you have never seen red slime algae inside a membrane housing you haven't lived yet! Its UGLY and smells like all get out. And it will plug a membrane pretty quickly. An annual or 6 month disinfection will help prevent this as wall as other bacterial and virus growth and is the smart thing to do.


Good to know. I might have to find the time to do this then. I do get some pink algae on that first cartridge, but it's never been a problem. Perhaps it's the lack of light, I don't know, but my lfs said it wasn't a concern, so I've never thought about it.

BTW, we've talked before, on a different reef site. Good to see you here. :)

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#22
AZDesertRat

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I have two dual inline TDS meters and never even turn them on. I use my HM Digital COM-100 handheld as it is much more sensitive, down to tenths of a TDS, and accurate. I plumbed a tee and ball valve in at all points I want to monitor and draw a small sample whenever I think of it then keep track of it all in a small log book. I am anal about water quality as it is my profession and has been for 37 years.

I consider the dual inlines a rough guide only, kind of like a litmus paper test, and never recommend them to anyone when they ask, I will always recommend a HM TDS-3 or TDS-4TM as the bare minimum at $20-$25 and the COM-100 if you are serious about water quality. I even went so far as to borrow a lab grade benchtop Thornton resistivity/conductivity meter for awhile just to confirm my handheld readings and was very happy with the results.

Water hammer can be a killer in an enclosed system. A properly placed check valve should eliminat this problem though. If it continues Spectrapure makes a small captive air or expansion tank they recommend for better operation and it works pretty slick.


http://www.spectrapu...m/St_alc_p4.htm

I don't have one myself but I have seen it in action.

Good to talk to you. I have been on N-R for almost 10 years now! I am presently on 8 reef forums and moderate or contribute to 4 of them on a regular basis.

Edited by AZDesertRat, 23 March 2012 - 08:23 AM.

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#23
GiantBen

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Been busy, so didn't get back to this right away. Sorry.
Just to clarify, I have a SpectraPure ProPlus 90. The date on the membrane is 1-3-10, although I'm sure I didn't start using it right away.

You cannot accurately test contaminants in RO, RO/DI or ultrapure water due to its agressive nature.

You need a TDS meter and the RO TDS should be somewhere around 96-98% less than the tap water TDS was to begin with. The RO/DI should be 0 TDS if it is working properly. Phosphate test kits and the like are not accurate with RO or RO/DI water.

Have you checked with your water utility to see if they do any treatment for corrosion control in the distribution system? Many utilities feed phosphates as a form of treatment and without very good DI you may not be capturing it all. You may need better resin or if you have a horizontal DI you may need a full size vertcal 20 oz DI for better contact time.

Are you using a handheld TDS meter or is it an inline? What are your tap water, RO only and RO/DI TDS readings?

I have not checked with my water supplier, but there are plenty of reefers around that don't seem to have a problem, so I don't think it is an unusual water supplier problem. I'm using the dual inline TDS that came with the unit. Incoming usually reads 2-3 TDS, out reads 0. When I first hook it up after a cleaning out, generally reads much higher briefly, which I am guessing is closer to the true reading of the water as it comes out of my hose.

The 6 month rule is an acceptable guideline in most cases. It is very easy to write the date on the unit or bracket and remember to do it all over again 6 months later, if anything it is better to err on the safe side.

If you have very good tap water conditions and don't mind some extra work on your part you can go longer than 6 months but you need to monitor both headloss or pressure drop at the RO membrane due to filter plugging or fouling and for the presence of chlorine in the treated water when the carbon begins to exhaust. It usually is best to have an additional pressure gauge on the tap water side of the sediment filter so you can compare it to the gauge on the RO housing at a glance for head loss and to have a low range chlorine test kit and use it.

This requires more work but it can save you a little money on replacements as long as you watch things closely. Its when you neglect to monitor things though and the headloss starts to affect RO membrane performance causing shorter DI life or chlorine gets to the RO membrane and damages it wher it actually ends up costing more. For most the 6 month rule works out best. It is also easyto disinfect the system while you have it down for replacements so another reason to do so.

It only takes a few psi pressure drop to start lowering the rejection rate so I like to keep clean fresh filters in place to keep the removal efficieny up and DI life long. Resin is as or more expensive than replacement filters.

The only ways to know when the RO membrane needs replacing is with your TDS meter and by watching your GPD. When the rejection rate starts dropping below say 95-96%, DI life is cut in half or more so requires more frequent replacement and drives the cost of operation up. Also when a membrane starts failing it may show up as reduced GPD or production rate as the membrane surface starts plugging.
My experience has been as long as you use the same high quality replacement filters Spectrapure provides, ie a 0.5 micron absolute rated sediment filter and a 0.5 micron 20,000 gallon carbon block, the membrane should last 5+ years and some users are seeing as long as 10 years of heavy use. Monitor your TDS and calculate your rejection rate every month or two and keep track or trend it over time. What are all four of your TDS readings on the two meters? What is your incoming or static water pressure? What is the pressure when the system is in operation? What is your water temperature and what is your exact measured waste ratio today? These things all aid in troubleshooting a system.

This is a good template they have on their site that walks you through testing your system.
http://www.spectrapu...ALC-FORMULA.pdf

Yes you can test phosphates in saltwater, just not in pure water with hobbyist type kits and meters.

I change the filters whenever the TDS stops reading 0. I have generally changed all three filters, but this time (die to advice recieved) I only changed the solica buster. I tested freshly mixed salt water for phos and got 0. Is there anything else that I could test (besides using a handheld TDS, as suggested) to ensure that the water quality is top notch? It feels like if fresh SW is testing at 0 TDS (via the inline) and teh phosphates are registering at 0, that the water must be pretty good.

Also, is there a way to open the membrane chamber? I couldn't get it open. I had heard from someone that they can get slimy and was going to check it and clean it, if possible.


Thanks again for the help.

#24
AZDesertRat

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You cannot accurately test phosphates in RO/DI water. Hobbyist test kits are not designed for ultrapure waters so are not accurate. TDS is the best and easiest measurement for RO and RO/DI water and all you need.

You can clean the membrane housing but be very careful as the membrane itself cannot take any bleach or chlorine or it melts the membrane fabric. You should be disinfecting the system at leas tannually following Spectrapures instructions, I recommend every 6 months at regular filter changessince you already have the system apart for maintenance. To clean the membrane housing the larger end unscrews and you remove the membrane before cleaning the empty housing. Normally if you keep up with the regular filter replacements and disinfection this is not needed though.
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#25
GiantBen

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Thanks for the replies. I'll just keep monitoring my TDS and sterilize my system. I started a new match today and the "in" TDS was 17, and gradually dropped to around 2. The out is now 1, which means I need new cartridges anyway. I'll order all three and re-sterilize.