RO filter died :-(

[Wes]

Ditching the RO membrane will allow you to make about 200 or so gallons of water vs 3000 gallons + , so who's doing the math again

ok so let's look at the cost of making 200 gallons using Randy's bulk price of $6 per canister and lets assume the 200 vs 3000 gallons is accurate and do a little rough math.

Using an average RO membrane, you actually use about 1,000 gallons of water to make 200 gallons of RODI water.

1000 gallons of water will cost you about $6.00.

So to make 200 gallons of RODI water you are at about
$6.00 [water cost] + $6*(200/3000) [DI resin cost] = $6.40/200g = $0.032 / gallon

to make 200 gallons of DI water you are at about
$6*(200/1000) [water cost] + $6 [resin cost] = $7.20/200g = $0.036 / gallon

This is not considering the upfront cost differences between an RODI unit and a canister w/ DI resin, or the cost of replacing membranes, etc...

If you don't consider those upfront costs you are only saving roughly $0.004/g or 0.4 cents a gallon by using an RO membrane. And can only make 75 gpd. The savings is actually less than that considering the equipment cost difference.

If you recharge your own DI resin you would be spending less per gallon than RODI water.

 

[pecan2phat]

Will just DI alone remove all the impurities that is subject to a RO membrane.

So basically, it's going back to the AP Tap Water filter but just less expensive for the media then.

 

[thirty5]

So let me get this straight..... All a RO membrane does is remove the TDS. So if i have 0 tds in my water before the RO then i dont need it????? Is there any amount that is tolerable of TDS for the tank??

 

[bad coffee]

0 tds is the only way to go.

I use only DI. I like the fact I can start the water and in less than a half hour I have a full bucket- 20 gallons. (Which figures out to about 960 GPD) I can make the water in the morning, dump in the amount of salt i need, and let it mix while I'm at work. I do the water change when I get home, and put everything away. No buckets, hoses, ect cluttering up the living room.

For me the main reason I switched was the waste water. Even though I don't pay for my water, I don't believe in wasting it for my fish tank.

ok so let's look at the cost of making 200 gallons using Randy's bulk price of $6 per canister and lets assume the 200 vs 3000 gallons is accurate and do a little rough math.

Using an average RO membrane, you actually use about 1,000 gallons of water to make 200 gallons of RODI water.

1000 gallons of water will cost you about $6.00.

So to make 200 gallons of RODI water you get
$6.00 [water cost] + $6*(200/3000) [DI resin cost] = $6.40/200g = $0.032 / gallon

to make 200 gallons of DI water you are at about
$6*(200/1000) [water cost] + $6 [resin cost] = $7.20/200g = $0.036 / gallon

You're forgetting the membrane cost.
So to make 200 gallons of RODI water you are at about
$6.00 [water cost] + $6*(200/3000) [DI resin cost] + (($50 [membrane cost] / ~20,000 [gallons per membrane] * 200 gallons)) = $6.90/200g = $0.0345 / gallon

 

[thirty5]

OK. I have to get a TDS meter then. And if my TAP is at 0 then i dont need the RO. Not really the cash factor, well everything comes down to cash. But the time factor sucks. Takes too long to actually make the RO water.

Thanks for the info.

I guess i will be getting a TDS meter. I like the one that was linked in this thread. a dual unit inline.

 

[cali_reef]

I don't live in the city now, but I don't think the water is $6 per 1,000 gallon. This would make NYC tap water more expensive than LA county water.

 

[Wes]

i don't live in the city but here on the Jersey side it is about $5.75 so i figured $6 for manhattan was a safe estimate. Someone who lives in the city should chime in so we can get a confirmation on the price.

 

[prattreef]

Thirtyfive,
There is absolutely no way your Tap water is 0 TDS. Far from it. NYC water is typically about 40 TDS which is very, very low and makes the DI alone option feasible. I wouldn't be surprised if your water measures 200-300. If this is the case, you will exhaust the DI resin quite quickly and it may not be worth it at all. RO is typically used before the resin to remove most of the dissolved impurities so that the DI resin isn't exhausted as quickly and if there are a lot of impurities in your water it does so much more cost effectively than DI alone.

Warren, DI alone will produce water that is equal to RO/DI provided you use high quality resins. It will not remove viruses and bacteria like an RO membrane will, but this is of little concern in a treated municipal supply situation. I wondered the same thing and contacted Randy Holmes Farley about it and he agreed water quality would not suffer at all. If you use untreated well water it might make a very big difference. I used to use TWP with fine results, it was just too expensive to replace the cartridges.

 

[thirty5]

Wow then my RO is connected wrong. I have my RO filter LAST after the DI. I have to fix that. I will have to get a meter to see what i am actually at. for a long time i was just using tap water with chemical to take out chlorine and stuff and i never had teh algae outbreaks as some people talk about. I will have to test my water to see what happens. Any thought on running through 2 di's? Just curious

 

[jhale]

thirty5 running through 2 DI chambers is ok, it will not give any purer water, but it will let the DI resin last longer between changes.

 

[thirty5]

thirty5 running through 2 DI chambers is ok, it will not give any purer water, but it will let the DI resin last longer between changes.

Ok that makes sense. I will have to get a meter to test my water. for now i wil just stay with the RO since i just got 2 new membranes.

 

[jhale]

For me the main reason I switched was the waste water. Even though I don't pay for my water, I don't believe in wasting it for my fish tank.

I'm with B on this one. I hate the thought of wasting that much water, I'll still use the RO for drinking water since when you take all the energy it takes to bring one gallon of bottled water to you the extra water used is worth it in that aspect.

I'm really liking the fast water making! I just did a 50G change today, and I have another 40G made and mixing already

Resin GB coming up? :Hydrogen:

 

[thirty5]

I'm with B on this one. I hate the thought of wasting that much water, I'll still use the RO for drinking water since when you take all the energy it takes to bring one gallon of bottled water to you the extra water used is worth it in that aspect.

I'm really liking the fast water making! I just did a 50G change today, and I have another 40G made and mixing already

Resin GB coming up? :Hydrogen:

Im hoping that I can get rid of the RO also. I dont use it for drinking water, i have a seperate filter for my water. Time is important.

 

[bad coffee]

Resin GB coming up? :Hydrogen:

I'd be down for $50 worth of changes.

Last time I ordered it from resindepot.com I believe the NON color changing stuff was about $200 a box. I have an inline TDS so I don't need the color chaning.

Somewhere, I saw a group buy of dual-inline TDS meters. I think they were about $18 each, if I remember correctly.

B

 

[gnatp2]

Ok, so this is making me think I should bypass my RO.

1) Making water MUCH quicker
2) Same quality
3) No waste water

Am I missing anything? The ONLY possible downside I see to bypassing the RO is the cost of DI resin which it totally outweighed in my mind by #1,2, and 3 above.

Any other arguments against bypassing the RO?

Nate

 

[thirty5]

Ok, so this is making me think I should bypass my RO.

1) Making water MUCH quicker
2) Same quality
3) No waste water

Am I missing anything? The ONLY possible downside I see to bypassing the RO is the cost of DI resin which it totally outweighed in my mind by #1,2, and 3 above.

Any other arguments against bypassing the RO?

Nate

Well not necessarily the same quality. YOu need to get a TDS meter to test the water to see what is in it. If your output after your DI gives you 0 tds then you dont need the RO. So test your water straight from tap. Then connect and test water out of filter WITHOUT RO connected. If you get 0 on the output then you are good to go without the membrane. I think that sounds right. If i am wrong someone else chime in...

 

[prattreef]

If you use high quality resin and you don't flow the water through it too quickly, you should get a 0 TDS reading regardless of the source water. The issue is the rate at which your resin will become depleted--- the higher the TDS of the tap water, the faster the resin gets depleted and thus the price per gallon will increase ---at what point this becomes prohibitive is a determination you need to make for yourself. Because of the low TDS in NYC tap water, this option may be a good one for SOME hobbyists.

 

[thirty5]

If you use high quality resin and you don't flow the water through it too quickly, you should get a 0 TDS reading regardless of the source water. The issue is the rate at which your resin will become depleted--- the higher the TDS of the tap water, the faster the resin gets depleted and thus the price per gallon will increase ---at what point this becomes prohibitive is a determination you need to make for yourself. Because of the low TDS in NYC tap water, this option may be a good one for SOME hobbyists.

Oh. flow matters through the resin? Cool. didnt know that.

 

[cali_reef]

I think resin gets saturated, not depleted

 

[gnatp2]

Sounds good. I'm gunna make the switch. My tap water has 40 TDS so this sounds like a great option for me.

Nate