RO DI water filter reccommedations
- Thread starter JeffCA
- Start date
Brian Prestwood
Premium Member
0 TDS! You making semiconductors 
The short answer to your question is almost any RO filter will do. Buy whatever is convenient.
If your tap water tastes bad then get a system with a holding tank that is designed for producing drinking water.
Details...
Lab grade water is around 8 TDS. Even that is overkill for our application. Bottled water for human consumption measures around 15 TDS. That is a good target.
The DI portion of an RO/DI filter is maintenance intensive. That's what you want to eliminate if you don't need it. Of course, with an RO system in front of of a DI system the DI system will require less maintenance.
Measure your tap water before you buy a filter. TFM RO filters remove approx 95% of contaminants. In other words, if your tap water measures 200 TDS (the worst I've seen in this area) RO filtering it will produce 10 TDS (200 * 0.05) water.
The water in Antelope measures around 180 TDS. RO filtering with a new membrane produces 4 TDS (98.4% cleaner) water. When it gets up to 15 TDS I'll replace the RO membrane ($50 for a 50gpd TFM membrane).
This is a 24 GPD Premier Manufacturing system I bought at CostCo for $150 a couple years ago. I get great drinking water out of it too. The 50 GPD Desal brand TFM membrane was purchased online from H2O Filter.
The trick with these TFM membranes is removing all the chlorine before the tap water gets to the membrane. You must replace the carbon prefilter every six months with normal use. If you are filtering a lot of water consider replacing the carbon prefilter cartridges with refillable cartridges. Refilling with GAC is much cheaper and they hold a lot more carbon than the disposable carbon prefilters.
The short answer to your question is almost any RO filter will do. Buy whatever is convenient.
If your tap water tastes bad then get a system with a holding tank that is designed for producing drinking water.
Details...
Lab grade water is around 8 TDS. Even that is overkill for our application. Bottled water for human consumption measures around 15 TDS. That is a good target.
The DI portion of an RO/DI filter is maintenance intensive. That's what you want to eliminate if you don't need it. Of course, with an RO system in front of of a DI system the DI system will require less maintenance.
Measure your tap water before you buy a filter. TFM RO filters remove approx 95% of contaminants. In other words, if your tap water measures 200 TDS (the worst I've seen in this area) RO filtering it will produce 10 TDS (200 * 0.05) water.
The water in Antelope measures around 180 TDS. RO filtering with a new membrane produces 4 TDS (98.4% cleaner) water. When it gets up to 15 TDS I'll replace the RO membrane ($50 for a 50gpd TFM membrane).
This is a 24 GPD Premier Manufacturing system I bought at CostCo for $150 a couple years ago. I get great drinking water out of it too. The 50 GPD Desal brand TFM membrane was purchased online from H2O Filter.
The trick with these TFM membranes is removing all the chlorine before the tap water gets to the membrane. You must replace the carbon prefilter every six months with normal use. If you are filtering a lot of water consider replacing the carbon prefilter cartridges with refillable cartridges. Refilling with GAC is much cheaper and they hold a lot more carbon than the disposable carbon prefilters.
Last edited:
Justin74
New member
I was going to get the ebay unit because of costs, but the price actually became very comparible when grouped with all the features the Typhoon III comes with. Features and a solid good name brand, I went with the Typhoon and couldnt be more happy. Definately a worth while investmant. It's plug and play right out of the box, just the in and the out and your good to go.Thank god too cuz I know it would take me all day to figure out a spagetti mess of tubes like that. I also opted for the DI bypass so I could also have great drinking water, it came with the bypass,pressure gauge,TDS meter, and automatic shutoff valve all inclusive making it a great deal, or a comparible deal to the ebay units if you tried to equip them with those extras.
-Justin
-Justin
Fragmented
New member
I also have the Typhoon and am very happy with it. The customer service is very good.
Brian Prestwood
Premium Member
First of all, I probably should have mentioned that I do use a post DI filter on my RO unit.
I spent the morning verifying my previous conclussion that DI isn't necessary with RO systems. Yes, I have too much time on my hands.
I was looking for a max TDS figure for make up water. I would expect that the public aquaria that use artificial water would have such figures but I couldn't find them.
As usual, WetWebMedia had the most material covering the subject. To paraphase, Bob (et al except Anthony) said DI probably isn't necessary but is cheap insurance.
One of the most notable items I found is that the IO salt formula (and several others) assumes the make up water is pure, no calcium or buffer.
I spent the morning verifying my previous conclussion that DI isn't necessary with RO systems. Yes, I have too much time on my hands.
I was looking for a max TDS figure for make up water. I would expect that the public aquaria that use artificial water would have such figures but I couldn't find them.
As usual, WetWebMedia had the most material covering the subject. To paraphase, Bob (et al except Anthony) said DI probably isn't necessary but is cheap insurance.
One of the most notable items I found is that the IO salt formula (and several others) assumes the make up water is pure, no calcium or buffer.
our Kent RO only unit has 0 TDS output (85- 90 TDS input water). We are adding an RO unit on the output regardless, because as was quoted, it is cheap insurance. I looked into the refillable GAC cartridges and didn't seem to be a significant cost savings.. maybe $10 - $15 a year, and that only after purchasing the refillable cartridge (if one didn't come with the unit already). But maybe I am just missing something
pepe.king.prawn
New member
I use a Devoneb "6-stage" somethin or other from eBay. ~$100 shipped along with an extra set of cartridges. it's labelled as 250gpd or something.. but it's more like 50-60 I'd say. Works well, and the water from it tastes fine, but I don't use a TDS meter. I work in several labs, and TDS is not a common measurement beyond a reference. Good luck with whatever you end up going with
