Avoiding Using an RO unit

[ScooterTDI]

So I can't really think of a good reason that I really need RO or RO/DI. Most of what is removed by RO systems is stuff that I am just going to add right back in when I make saltwater. I am only really concerned about chlorine, chloramine, nitrate, phosphate, and heavy metals in the tap water, so I am considering switching to a system in which tap water is passed through a column of :

1) activated carbon to remove chlorine/chloramine, some organics, and heavy metals
2) zeolite ammonia remover to remove the ammonia released by the breakdown of chloramine
3) exchange resin nitrate remover (easily rechargeable)

When doing a water change, I would add some lanthanum chloride to the processed water and let the precipitate settle out before transferring to another vessel to mix saltwater.

For topoff, I wouldn't bother with the lanthanum treatment, because I am running topoff through a kalk stirrer, so most of the phosphate is going to precipitate out and never reach the tank.

The expendables are carbon, ammonia remover, and lanthnum chloride. All of which are fairly inexpensive. I haven't done the math yet, but it seems like this might be cheaper to operate than RO/DI.

Anyone see any problems with this?

Scott

 

[Randy Holmes-Farley]

It may work fine, but it sounds like a lot of work, and you can't be assured it will adequately remove everything without measurement.

 

[sowellj]

It seems to me that by the time you do all of that, you will be in the same ballpark price of an RO/DI unit so why not just get one?

 

[ScooterTDI]

I don't really think it will be much more work/time than maintaining an RO/DI. I just buy one of those cheap multistage household water filter systems, fill it with the media, and periodically test the effluent. I can probably estimate when the media should start becoming spent and increase testing frequency when I know the media is on its way out.

Just a guess, but I don't think this would cost nearly as much to operate as an RO/DI. Initial expense, wasted water, replacement membranes, and replacement cartridges all add up. I thinkthe media I plan to use should last quite awhile between replacement/recharge.

Scott

 

[Randy Holmes-Farley]

If it were my water, I'd want a sediment filter too. I get a ton of sediments in the water from corroding pipes, etc., and I wouldn't want them getting to the tank without my knowing what they were in detail.

 

[chuckreef]

3) exchange resin nitrate remover (easily rechargeable)

What do you mean exactly by this step?
What are your source water parameters?

 

[ScooterTDI]

I thought about that, but I figured sediments would settle out along with the lanthanum precipitate when doing water changes or in the bottom of my top-off container. Any idea on the settling velocity of particulates found in tap?

Scott

 

[LPS_Blasto]

Why reinvent the wheel?

You can buy a 3 or 4 stage RO unit for under $100. Thats good enough for your reef tank. Use your TDS meter to tell you when it's time to change the cartridges. Takes all of 15 minutes to change the cartridges and repack the DI resin and you'll do that once a year at the most.

I don't like fussing with equipment though. Maybe it just comes down to differing personality traits? :beer:

 

[ScooterTDI]

3) exchange resin nitrate remover (easily rechargeable)

What do you mean exactly by this step?
What are your source water parameters?

There are a number of ion-exchange resin nitrate removers on the market for freshwater aquarists. I figured I'd just use one of those products. I was looking at the Fluval brand the other day. It says one jar can remove 25 mg/L from 50 gallons. That works out to a capacity of about 4.75g of nitrate (not sure if they are measuring nitrate or nitrate-N though).

Source water has ~1 mg/L PO4 and ~0-5 mg/L NO3.

Scott

 

[ScooterTDI]

Why reinvent the wheel?

You can buy a 3 or 4 stage RO unit for under $100. Thats good enough for your reef tank. Use your TDS meter to tell you when it's time to change the cartridges. Takes all of 15 minutes to change the cartridges and repack the DI resin and you'll do that once a year at the most.

I don't like fussing with equipment though. Maybe it just comes down to differing personality traits? :beer:

I don't see how my system involves that much more work/time. It would take 15 minutes to empty and refill the media with this system as well.

Scott

 

[jason2459]

Sounds like a lot more maintenance and expense to me. You say it's stuff you'll add back in when making the water. But did you think that now you might have to much of this "stuff" by not removing the large amounts of heavy metals and then also adding in traces of it with the salt mix?

 

[ScooterTDI]

I was referring to things like carbonates, sodium, chloride, calcium, magnesium, etc. The amounts of these in tap water are pretty insignificant when compared to seawater. Heavy metals should be largely removed by the carbon. For top-off water that is passing through the kalk stirrer, most of the heavy metals are precipitated anyway.

Scott

 

[jason2459]

I'd worry that the carbon is not removing enough of the desolved solids which is what the Ro and DI stages would take of. Plus, if the carbon was efficient enough for that then you'd be swapping out carbon a lot.

 

[ScooterTDI]

I'm not sure I understand. I don't expect carbon to remove everything that RO or DI would. I mainly just want it to react with chlorine/chloramine. It will retain this activity for a long time. The heavy metal removal is just an added benefit. As I said, the kalk stirrer will remove heavy metals from the top-off.

Scott

 

[jason2459]

try it out and let us know the results. Would also be interesting to know the long term cost comparison vs. ro/di units.

 

[luther1200]

I can't imagine this being cheaper or easier than a RO/DI. In the time since I have had my RO/DI (1 year) I have spent, $80 used RO/DI+ $40 new membrane+ $20 (2) carbon blocks+ $5 (2) sediment filters+ $10 (1) DI resin. For a total of $155. The DI is almost spent but it took a whole year, and I replaced the carbon block and sediment 6 months. I think $155 is very resonable. Getting a used unit was a big help, if you look around I'm sure you can find 1. Then just get a new memnbrane for $40 and your good.

 

[chuckreef]

I'm not certain, but I think these products are intended for closed systems where the water continually circulates thorugh the media (resin). I.e., it is not reduced from 25 to 0 all at once.

At 1 ppm in your influent influent, it may work in a single pass, but, it is also possible that it may require you to recircualte the tap water continuously through the resing for a while (24 hours) for it to work. That sounds tedious to me (compared to opening a valve and walking away while the tank fills slowly).

Maybe the rest of your idea followed by a standard 10 inch anion column would work better than the Fluval product. The cost is about the same and I have to imagine there is much more than 150 g of anion resin in a standard anion cartridge. You could also try buying the bulk anion resin alone and using it in what ever apparatus you planned to put the fluval resin in.

In the end, I think it really depends on your source water. If you have really low TDS source water, this may work for you. For most reefers, I beleive the RO membrane removes many impuritites that would otherwise rapidly deplete the DI resins. I think the same substances would waste the fluval resin in short order. Presuming I would need two of these 150g packages to make 50 gallons of water, I don't think I'd see any cost savings myself.

Chuckreef

There are a number of ion-exchange resin nitrate removers on the market for freshwater aquarists. I figured I'd just use one of those products. I was looking at the Fluval brand the other day. It says one jar can remove 25 mg/L from 50 gallons. That works out to a capacity of about 4.75g of nitrate (not sure if they are measuring nitrate or nitrate-N though).

Source water has ~1 mg/L PO4 and ~0-5 mg/L NO3.

Scott

 

[cbrivkalns]

I actually tried to do something very similar based on a plan I found on the lifestock.org website. For the record, I have chloramines in my water supply...

Long story short, it didn't work too well. I had a 3-foot 1.5" PVC pipe packed with Fluval carbon and it only reduced the chloramines a little (as measured with a Red Sea Fresh Water test kit). I originally tried the Kent Reef Carbon (cylindrical pellets), but since it didn't pack as well it was even less effective than the Fluval media.

As experiments go it really wasn't that expensive, and I'm glad I at least tried it. That being said, I'll be purchasing an RO-DI before I fill my new tank with water.

Cheers!

 

[lordofthereef]

I could be wrong, but it sounds like you would be just as content with something like a brita filter that they make even for on the tap use. I don't see a reason to go beyond that if you are not wanting and/or willing to go with an RO unit.

 

[lordofthereef]

I can't imagine this being cheaper or easier than a RO/DI. In the time since I have had my RO/DI (1 year) I have spent, $80 used RO/DI+ $40 new membrane+ $20 (2) carbon blocks+ $5 (2) sediment filters+ $10 (1) DI resin. For a total of $155. The DI is almost spent but it took a whole year, and I replaced the carbon block and sediment 6 months. I think $155 is very resonable. Getting a used unit was a big help, if you look around I'm sure you can find 1. Then just get a new memnbrane for $40 and your good.

As far as that goes I recently read a post (I think it was by a user NINEONEONE or something along those lines) who was able to piece together all of the parts he needed to make an RO unit for a total of ten bucks from Habitats for Humanity. This was all minus filters of course, but that might tac on another 30-40 bucks.