Is RO enough?

[Reefski's]

i am thinking of buying a Large RO unit. much cheaper over time. it can make 450 gallons per day. not that i need that much but i can also supply my friends.

my TDS levels right now are about 160. i think they are higher in the summer and fall until it starts to rain here.

can i use only RO water with no DI. i think it will leave <10ppm TDS.

i will be using this for my makeup/Kalk water and NSW for whater changes.

Carl

 

[crumbletop]

From what I understand, the RO will not get things like phosphates. The DI normally gets these. One of the big reasons (for me) was to keep phosphates out of my system as much as possible, which means having DI.

If I were you, I'd go for a 75gpd RO/DI with a Dow Filmtec membrane. I have a typhoon unit from http://www.airwaterice.com/category/reefkeeping/ and am very pleased with it.

Jack

 

[nemo g]

ive got the typhoon as well.

i tested my water before it goes in, and has no phosphate. and for now, just a temp tank, im only using ro and saving the DI, but my tds is testing nice and low at 3.

so it depends on your water.

 

[AmerICHans]

Many people overlook this, but distilled water is the way to go. It's water stripped down to it's core. No phosphates or anything else. You save a ton of money. Walmart sells distilled water at 62 cents per gallon. Or buy your own home distiller which isn't that much compared to what you'll spend in the long run on RO/DI systems and membranes. Not to mention maintenance. Also, get OSMO-Prep from Kent, it adds the right stuff back to distilled and RO'd water.

 

[crumbletop]

There isn't anything missing from RO/DI that you need. You shouldn't be adding anything back into the water except salt and other necessary additives based on test kit measurements (buffer, Kalk, ...). You don't need OSMO-prep.

A couple of things regarding distilled. In the past the distillers used copper pipes -- not good for reef aquariums. I'm not sure if any distillers still use copper or not. Also, at 62 cents per gallon, my RO/DI has more than paid for itself. My city water is $4.08 per 200 gallons of RO/DI (if you go with 1000 gallons of water used to make 200 gallons). If I spend $200 on an RO/DI, and $8.16 on 400 gallons of water, that comes to 52 cents per gallon. My RO/DI will be much cheaper than that as I am not replacing my entire RO/DI setup with a brand new one every 400 gallons....

Jack

 

[Spuds725]

The math on cost to run also depends on the quantity of water you use... on smaller tanks, it might be more cost effective to get bottles of distilled...

I easily use 1500 gallons per year-- I don't want to spend $800 on bottled distilled...

For me RO/DI is the least expensive option for "pure" water-- I use about $30-40 per year in DI resin and replacement filters.... the initial cost for a good RO/DI may make people not want to get one... the ongoing cost is lower in most cases--FYI-- I have well water so their is no ongoing cost for purchasing my raw water other then the power to run my well pump.

 

[sushi chef]

I think a home distillation unit would actually be more expensive than an RO/DI unit. Distillation units are cheaper to buy than RO DI, but not by too much. The energy used to heat up the water will really add up over time. Home distillation units are also pretty small capacity wise, so you'd have to make batches continuously unless you opt for a much more expensive industrial unit. Also, distillation does not remove volatile chemicals, so you'd probably need to run the distilled water through some DI resin.

The RO DI process uses no electricity and, at least where I live, water is much much cheaper than electricity; the cost of water is practically negligible. Changing the filters don't cost all that much, and with the recent 2 trillion percent hike on electricity rates in Texas through TXU, RO DI is definitly the better option.

That's just for me though, other states may have cheaper electricity.

 

[TimFountain]

I had an RO only fliter, and some algea problems. All gone once DI added.... Just my experience.

 

[AZDesertRat]

The only way that question can be answered accurately would be to know what your water quality is to begin with and the rejection rate of the RO system you are looking at. You may have only 160 mg/L TDS but it could be ful of copper, nitrates, phosphates and other things. As for the membrane you will find most large capacity systems do not have the 98% rejection rate that home use size membranes do. You will be very lucky to find one at even 90% rejection rate in that high a capacity.
Look at the GE Merlin system that www.airwaterice.com sells as an example of higher capacity filters.