Need Prime when running RO/DI
 

Hi everyone,

I am filling my new tank with RO/DI water (over the next week.....) and was wondering if I need to use something like Prime to de chlorinate. I have used Prime for years on my fw tanks and had not added it so far to the RO/DI water I am putting into the SW tank. It is supposed to remove ammonia, chlorine, and chloramine. Ammonia will be handled by the cycling process but are the other two removed by RO/DI?

thanks,

Palmer

No prime required. :wink:

RO/DI removes everything from water - repeat: EVERYTHING.

Thanks (one less thing to buy more of) I have never read anything about using it in reef tanks but it just dawned on me I hadn't been adding it and old habits are hard to lose!

Palmer

Except the wetness.. :lol:

The chlorine and chloramine and many other chemicals are taken care of by the carbon cartridge before the RO membrane - chlorine can severly damage a RO membrane for example, so the initial carbon filtration helps with that. Metallic ions, etc are usually taken out by the membrane and by the DI resin after the RO membrane, hence you don't need Prime.

Huh!

Silly Leah, You can't remove the Wetness of water. :D

when you have a RO/DI unit the DI will remove the remaining Total disolved solids that are after the membrane. This will result in 0 TDS. These units make the purest water available.

If the RO unit is being properly maintenanced, then the the water coming from it will be fine. I don't have my own unit yet, so I buy top off water from those machines in the grocery store. That water I add prime to, because who knows how good those machines are taken care of. Considering how cheap a dose of prime is, why risk it?

Adding Prime and other water conditiions may adversely affect skimmer performance. This is because such conditioners can, among other things, change the surface tension of the water which is how a skimmer works.

That's not quite true, but accurate enough for the question in question. :D

http://reefkeeping.com/issues/2005-05/rhf/index.php

Ya It doesn't remove the wetness LOL

Uhm, you didn't read the link did you? I will paste some of the pertinent information just for you seeing as the link wasn't good enough.

As per Randy-Holmes Farley:

"Also, in order to get a sufficiently fast flow of water through the membrane, membrane pores are actually significantly larger than a water molecule. For this reason, some of the molecules of compounds that are somewhat larger than a water molecule can still get through (sodium ion, for example, is not perfectly rejected).

However, at the small end of the spectrum [referring to particle size] a number of compounds can pass through a reverse osmosis membrane to some extent and are, therefore, of concern to reef aquarists. These include carbon dioxide (CO2), ammonia (NH3), hydrogen sulfide (H2S, especially a concern with well water) and silicic acid (Si(OH)4, which is the uncharged and predominate form of silicate at pH values below 9.5). All of these should be trapped by a functioning DI resin (discussed below), but can still be a concern.

In the case of CO2, for example, there can be a lot of it in certain well waters, and DI resins may become rapidly depleted because the CO2 so readily passes through RO membranes (how to deal with this is discussed later in this article). As another example, ammonia that comes from chloramine in the water can be significant, and is one reason that RO/DI is greatly preferred to RO alone in those situations where chloramine is added to the tap water."




"A DI resin traps all charged molecules passing through it, and leaves uncharged (neutral) molecules free to pass through. Water, for example, passes through it, as would other uncharged inorganic molecules such as oxygen (O2), nitrogen (N2) and chloramine (NH2Cl, if any remained from the previous filters). Uncharged organic molecules also pass through a DI resin, including ethanol (CH3CH2OH), methanol (CH3OH), methane (CH4), propane (CH3CH2CH3), carbon tetrachloride (CCl4), and methylene chloride (CH2Cl2)."




"RO/DI is likely the most effective way for reef aquarists to adequately purify all tap waters they are likely to encounter. Most aquarists will find that a standard system consisting of a sediment filter, a carbon filter, a reverse osmosis membrane, and a deionizing resin cartridge is perfectly suitable. It is also useful to have the ability to measure the conductivity of the effluent inline, and to measure the pressure across the RO membrane.

In some cases, it may be desirable to degas the incoming tap water if it contains excessive carbon dioxide. It may also be desirable to have two DI cartridges in series if there is a lot of silica or other easily penetrating problem ions in the RO permeate. If you have well water that smells bad or has other peculiarities, it may be worth discussing the issue with a top-of-the-line RO/DI system manufacturer to make sure that you are treating the water appropriately."







It would have been much easier if you would have just read the article yourself. ;)

Didn't read either LOL. I can never read any of Farley's stuff, to much chemistry geek speak. I don't remember much from chemistry LOL

That's why I only posted the information that was presented in easy reading terminology.