RODI with carbon filter first, is this normal?

[Levinson]

Greetings, a noob here. I've ordered a RODI purifier online recently and just opened it up.
While reading the instruction online (and the writings on the unit) I've just realised that the unit has the carbon filter as its first filteration then the sediment filter.
This is different from other RODI units that I've seen online which has sediment first then carbon.
I'm going to call the seller tomorrow to ask about it but just wanted to ask if this is normal / done elsewhere.
I haven't put them together yet and I guess I can make changes in the order if I wanted to. (except then the labels on the unit would be wrong)
Cheers

 

[PbMan26]

That does not seem correct. Sediment should be first...

 

[Redfoxtang]

Ideally this will still work as you still have carbon/sediment then RO membrane then DI. As long as your not filtering sand water I think you’d be ok. Now that I think about my RO water drinking system is like that and it’s from GE. But if it’s easy to flip the filters that what I would do for piece of mind.

 

[KStatefan]

The sediment filter is there to protect the carbon filter and should go first.

 

[greg 45]

I have a 1000 gpd unit from aqua/fx. I run carbon 1st then 3 sediment cartridges , before the membrane. When I ran a smaller unit with the sediment filters first , carbon 2nd the dual membranes would clog up in over a month . The fines from the carbon will clog the membranes . I cut them open and they were the color of carbon . I have been running the aqua/fx unit for over a year with no issues .

 

[chipmunkofdoom2]

I have a 1000 gpd unit from aqua/fx. I run carbon 1st then 3 sediment cartridges , before the membrane. When I ran a smaller unit with the sediment filters first , carbon 2nd the dual membranes would clog up in over a month . The fines from the carbon will clog the membranes . I cut them open and they were the color of carbon . I have been running the aqua/fx unit for over a year with no issues .

Did you flush the carbon blocks first? Carbon blocks will produce dust and clog the membrane if you don't flush them first. I flush my new carbon blocks for a half hour before allowing the water to go into the membrane. I run two carbon stages and flush each individually so the dust from the first doesn't clog the second. If the carbon block still produces enough dust to kill your membrane after flushing, that type of carbon block is low quality and should not be used. It doesn't mean that you should move away from the industry-standard filter arrangement.

The RO filters we use are in a very specific order for a reason. In addition to cleaning the water, the filters in our RO systems also protect the downstream stages from premature failure. The reason carbon blocks need to go after the sediment filter is because the small pores in carbon blocks can clog easily if the incoming water isn't filtered first. Carbon blocks are expensive when compared to sediment filters. If a carbon block clogs before it loses the ability to remove chlorine and VOCs, you've essentially used an expensive carbon filter like a cheap sediment filter.

 

[Levinson]

Thank you all for your input. It sounds like I should switch the carbon with sediment even if the seller says to have the carbon first. Will hear what the seller says then put it together tomorrow.

Did you flush the carbon blocks first? Carbon blocks will produce dust and clog the membrane if you don't flush them first. I flush my new carbon blocks for a half hour before allowing the water to go into the membrane. I run two carbon stages and flush each individually so the dust from the first doesn't clog the second. If the carbon block still produces enough dust to kill your membrane after flushing, that type of carbon block is low quality and should not be used. It doesn't mean that you should move away from the industry-standard filter arrangement.

So I should flush carbon before putting it in? How is it done? Do I put the carbon in the case then put it under the running tap water for a while?

By the way, with the unit I have, the carbon comes in a plastic bag and you fill-up the carbon into a plastic container. It's not one of those where you get the pre-made carbon-filled cylinder and simply put it in.

 

[K7BMG]

What brand is your RO unit?
You have not mentioned a DI stage?
Is this a drinking water setup or one for a reef tank?

To my knowledge there is a difference in the carbon used for drinking water systems, vs ones designed for reef tanks.

 

[Levinson]

What brand is your RO unit?
You have not mentioned a DI stage?
Is this a drinking water setup or one for a reef tank?

To my knowledge there is a difference in the carbon used for drinking water systems, vs ones designed for reef tanks.

It's sold for saltwater/reef aquarium use by the people who sell aquarium stuff so I'm guessing it's not for drinking (unless they are not being very honest with their product). The brand of RO unit is 'Vontron', judging by the writings on the package, I'm pretty sure it's a Chinese brand.

 

[KStatefan]

Thank you all for your input. It sounds like I should switch the carbon with sediment even if the seller says to have the carbon first. Will hear what the seller says then put it together tomorrow.



So I should flush carbon before putting it in? How is it done? Do I put the carbon in the case then put it under the running tap water for a while?

By the way, with the unit I have, the carbon comes in a plastic bag and you fill-up the carbon into a plastic container. It's not one of those where you get the pre-made carbon-filled cylinder and simply put it in.

I have a bypass valve installed so I can shut off water to the membrane to flush the carbon I have two carbon filters so I install the first one and leave the second canister empty and flush then install and flush again.

You can disconnect the output line and accomplish the same thing.

 

[K7BMG]

Does it have a resin canister?

The problem with cheap carbon.
It can cause HLLE on tangs, or so the consensus says.
I have not seen scientific proof of this in a report, but have seen the result of carbon induced HLLE on my Kole Tang.

My Tang had HLLE prior to me introducing carbon.
It had been under control and receeding, once I figured out a better more nutritional diet for him.

Several months went by and for what ever I decided to put a carbon canister in the system. Used the high end Rox.08 from BRS.
Within the week the HLLE started to increase on him.
Doing research and finding out carbon can cause this I pulled it from the system. This stopped the progression of HLLE on the Kole and I will never use it again. I can only imagine if I used a cheap carbon vs the Rox.08 the tang would have died.

So if you have a cheap carbon canister, well maybe you might want to toss the cartridge for a quality one of use it and avoid Tangs, or closely moniter them.

 

[Levinson]

Does it have a resin canister?

The first and the third bottom canister(?) has the plastic case that you are meant to fill up with carbon and DI resin. The middle one has a sediment filter in it. I should have posted the picture first.
I don't have any plans to have Tangs in my tank but thanks for the info. I'm sure the knowledge would be of use at some point down the line.

 

[Levinson]

I've got a response from the seller and they say that the reason for the sediment coming after the carbon is to protect RO filter (which is more expensive) from the dust coming off carbon... which also sounds kinda... convincing.
They recommended not to change the order of the filters. But then again, the order most people are using, sediment -> carbon -> RO -> DI, can't be wrong.
Dang, to think I'd be swayed so easily... I'm torn between the options!!!

 

[Natedogg1978]

I have a 1000 gpd unit from aqua/fx. I run carbon 1st then 3 sediment cartridges , before the membrane. When I ran a smaller unit with the sediment filters first , carbon 2nd the dual membranes would clog up in over a month . The fines from the carbon will clog the membranes . I cut them open and they were the color of carbon . I have been running the aqua/fx unit for over a year with no issues .

I also use an aquafx barracuda glacial, but run sediment first, then ( 2) chloramine blasters.

curious, if you are running three sediment cartridges, how many cartridges or total stages do you have?

 

[Levinson]

I just filled the housings, one with carbon and one with DI resin. Being a noob, I made a mass in the process but I could do better next time.
Putting the dry carbon into the housing, there's quite a bit of dust so I asked the seller about how I should wash it but he says not to wash it as the housing has its own filter which will take care of the dust and just use it as is. Hmmm...
Still, I'm tempted to just take out the carbon housing unit from the canister and put the housing inlet under running tap water to flush whatever I can. Is this a good/bad idea?

 

[Opus]

I've got a response from the seller and they say that the reason for the sediment coming after the carbon is to protect RO filter (which is more expensive) from the dust coming off carbon... which also sounds kinda... convincing.
They recommended not to change the order of the filters. But then again, the order most people are using, sediment -> carbon -> RO -> DI, can't be wrong.
Dang, to think I'd be swayed so easily... I'm torn between the options!!!

They are telling you that because they are using loose carbon. Most people use a carbon block that forces it thru very small pores. Most use a 5 or 1 micron rated carbon block. Yours isn't going to really stop any thing and probably will have a lot more dust over its life. Personally I would invest in a carbon block. I've only seen loose carbon used in specialized instances.

 

[Levinson]

They are telling you that because they are using loose carbon. Most people use a carbon block that forces it thru very small pores. Most use a 5 or 1 micron rated carbon block. Yours isn't going to really stop any thing and probably will have a lot more dust over its life. Personally I would invest in a carbon block. I've only seen loose carbon used in specialized instances.

Thanks Opus, that explains a lot of things! I should go find a propper carbon block and swap the order to sediment to carbon. I screwed up again but at least I can use the carbon in the tank.