Why RODI

[James77]

It enables you to strip out pretty much every contaminant and start from scratch with the water.

My city water has a pretty low TDS, but there are still city lines that may be lead pipes, and there is obviously copper pipe and solder throughout the house.

With my freshwater tanks, I still run the water through the sediment and carbon blocks.

 

[oldbob50]

Straight RODI water is too acidic for FW or SW. Your salt mix corrects the PH for SW use but you would have to add some buffering to it for FW use. Typical FW PH is in the 6.8 to 7.2 range. My RODI water measures 6.0 (limit of the test kit) or less. Thats why I have a spring fed, flow through system on my FW tank. My spring produces water that is PH 7 and a TDS of 50 to 60. I've set it to do a complete WC every day and the fish love it. As to W1ngz's comment on serious planted tanks I have to agree. I find corals easier to keep than many of the FW plants.

 

[James77]

I run RODI water. Can I get advice from you guys? My system has 3 canisters then 2 membrane canisters and finally 1 last canister with the TDS meter on it. I make 25 gallons a month for water changes and 15 gallons a week for the ATO.
My question is when do I change out my filters? The first one has turned brown. The second is getting brown. The third is still white. The canister with the TDS meter has some kind of media in it instead of a filter. When should I change that media out? TDS is still reading 1 to 0 on the discharge of the whole unit.
I have just never ran RODI and I don’t have any friends that have any experience with these units. Any advice would be helpful.

Well, there is brown, and there is BROWN.

It can't hurt to replace your sediment filters if they are quite brown. They are the cheapest of the filters. TDS is what matters, and you should keep track of how much TOTAL water goes through the carbon blocks. The carbon blocks remove the chlorine, and you should follow their rating.

Regardless, it is good practice to replace the sediment and carbon filters every 6 months, regardless of water put through them.

FWIW, here is my filter. I thinks its about 5 months in and I will likely replace soon only for time. Plus I get to try positng a photo lol.

Edit....I am going to miss having to use photobucket from the other site!

 

[Wildblue4]

I have a BRS unit as well. Do you get your replacement cartridges from them or is there a cheaper local place to get them? Are they just standard water cleaning cartridges?

 

[James77]

I have a BRS unit as well. Do you get your replacement cartridges from them or is there a cheaper local place to get them? Are they just standard water cleaning cartridges?

The filters are pretty standard. I do go with BRS simply because I order so many other things from them.

Spectrapure has some high quality specific filters like silicabuster. But for the most part filters are filters.

Hard to beat BRS for shipping costs and selection though!

 

[Flippers4pups]

To add to the discussion about the use of RO/DI water. Most municipal water treatment facilities have switched from chlorine to chloramines. This disinfectant, unlike chlorine, does not dissipate easily. It can stay in water much longer.

The unknowns about what is in your tap water can be found in your cities water report. It will break down the list of contaminants. The thing is it's a one time report for the year. Contaminants change throughout the year depending on rain amounts, runoff, agricultural insecticides/ fertilizers, industrial wastewater.....etc in your location. Heavy metals, etc and the above can be toxic to marine life.

Your local water maybe "hard" water/well water. Deposits on faucets, showerheads white In appearance may be deposits of silica. Silica and silicate is used by diatoms.

Though some hobbyist can claim no problems with use of treated tap (using a de-chlorinator such as Prime or Aquel) they run the risk of tap water contaminants accumulating in their systems over time.

So using a properly maintained RO/DI unit is a security factor in keeping marine sensitive animals such as coral, invertebrates and fish.

I don't trust my tap water, nor should you.

 

[GSnake]

The biggest reason it's used in marine is because corals are more sensitive. And I found the marine system is very sensitive. I had used tap water when I started with mediocre results. Corals may have been stressed too, but they were growing somewhat. My biggest issue was lots of gha. High bacteria counts ( string like filaments on rocks) and cyano. When I switched to rodi these issues were 0. Or at worst minimized greatly. Like 95%

 

[Buckeye Hydro]

I run RODI water. Can I get advice from you guys? My system has 3 canisters then 2 membrane canisters and finally 1 last canister with the TDS meter on it. I make 25 gallons a month for water changes and 15 gallons a week for the ATO.
My question is when do I change out my filters? The first one has turned brown. The second is getting brown. The third is still white. The canister with the TDS meter has some kind of media in it instead of a filter. When should I change that media out? TDS is still reading 1 to 0 on the discharge of the whole unit.
I have just never ran RODI and I don’t have any friends that have any experience with these units. Any advice would be helpful.

From our FAQ's :

When should I replace my filters?​

A good rule of thumb is to replace your sediment filter and carbon block after six months. A more precise way to maximize the usable life of these two filters is to use a pressure gauge to identify when pressure reaching the membrane starts to decline. This is your indication one or more of the prefilters (all the filters that touch the water before it reaches the RO membrane) is beginning to clog.

Also be cognizant of the chlorine capacity of the carbon block. A good 0.5 micron carbon block for example will remove much of the chlorine from 20,000 gallons of tap water presented at 1 gpm. Some original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons. Remember that all the water you process, both waste water and purified water, goes through the carbon block.

Regarding your RO membrane and DI resin, use your total dissolved solids (TDS) meter to measure, record, and track the TDS (expressed in parts per million [ppm]) in three places: 1) tap water, 2) after the RO but before the DI, and 3) after the DI.

The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 ppm. Common readings are 100 to 400 ppm. So for sake of discussion, let's say your tap water reads 400 ppm. That means that for every million parts of water, you have 400 parts of dissolved solids. How do we go about getting that TDS reading down to somewhere near zero?

If you do some experimenting with your TDS meter, you'll note that your sediment filter and carbon block do very little to remove dissolved solids. So with your tap water at 400 ppm, you can measure the water at the “in” port on your RO membrane housing and you'll see it is still approximately 400 ppm.

The RO membrane is really the workhorse of the system. It removes most of the TDS, some membranes to a greater extent than others. For instance, 100 gpd Filmtec membranes have a rejection rate of 96% (i.e., they reject 96% of the dissolved solids in the feed water). So the purified water coming from your 100 gpd membrane would be about 16 ppm (a 96% reduction). Filmtec 75 gpd (and below) membranes produce purified water (a.k.a. “permeate”) more slowly, but have a higher rejection rate (96 to 99%). The lifespan of an RO membrane is dependent upon how much water you run through it, and how “dirty” the water is. Membranes can function well for a year, two years, or more. To test the membrane, measure the TDS in the water coming into the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membrane’s advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce purified water more slowly as their function declines.

After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the TDS in the RO water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm, your resin needs to be replaced. Sometimes you'll hear people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane sending the DI resin high TDS water. This will exhaust the resin quicker than would otherwise have been the case. Sometimes the problem is poor quality resin – remember that all resins are not created equal.

Additionally, don’t forget to sanitize the entire system at least once per year, and wash and lube your housing o-rings with food-grade silicone grease every filter change.

Russ