RODI micron question

[Myka]

I was just digging up some links for another thread, and came across Randy Holmes-Farley's comments on what passes through RO membranes:

"However, at the small end of the spectrum 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."

Obviously, there isn't a 100% fail rate with these compounds either though.

[Craigdillman]

Check out aquasafe Canada there to RODI machines are awesome they have quick shipping and solid prices on filters. Got a setup with drinking tap and 4 gallon too off container for round. 185$ ish

[StirCrazy]

Originally Posted by Myka

I was just digging up some links for another thread, and came across Randy Holmes-Farley's comments on what passes through RO membranes:

yup not 100% in another article by him, he does tests and finds he normaly starts out with about 2ppm and the ro brings it down to about .1 - .2

now in a healthy reef aquarium when you test the water you will probably see 0 as your bacteria will reduce it rather quickly.

now having said all that membran selection is obviously important also, as diferent brands and different construction methods give different rejection ratesof different elements, the rejection rate advertised is just for stabalized salt.

I just reviewed some of my documents and amonia is a trickey one, it can either pass through or be rejected depending on the PH and temp of the water which would explain why I always got 0 amonia out of my RO in Victoria and here in kamloops (city is fed by ro system) I will just post the explanation from my Dow lititure.

"
Dissolved gases like ammonia (NH3) will not be rejected by an RO membrane; however, NH3 is in equilibrium with the ammonium cation (NH4+), as defined by the following equation:

NH3 + H+ <---> NH4+
Decreasing the pH and/or temperature will convert NH3 to NH4+, which is rejected by the FILMTEC RO membrane.
For example, as long as the temperature and pH are less than 40°C (104°F) and 7 respectively, more than 95% will be present as NH4+ and the rejection should be better than 98%. However, if both parameters are allowed to increase, the amount of ammonia will also increase, accompanied by a corresponding decrease in rejection by the RO membrane. "

so the hardness of your water does make a difference in the rejection, which would lead to the question if your RO runs after the water softener would this help in that area? would be neat to see if some one has one if they could do with and with out testing.

Steve

[Myka]

In my system, pH is 7.5 to 7.8 after the carbon block and I use 72-75F water. I just use a 1 micron carbon block, and it handles all the chloramine and chlorine. I'm going to test ammonia after my RO membrane now - I'm curious how much is getting to my DI resin.

Also of note, NH4 generally isn't toxic to fish, but NH3 is lethal.

[StirCrazy]

Originally Posted by Myka

In my system, pH is 7.5 to 7.8 after the carbon block and I use 72-75F water.

PH might be a bit high but let me know what your getting, another problem brought up by Randy is the test kits we use are basically junk for lower concentrations and quite often give bad readings, but who wants to spend the money for a good one......

on another note, why is your tap water so hot?

Originally Posted by Myka

Also of note, NH4 generally isn't toxic to fish, but NH3 is lethal.

ya NH4 has to be pretty high to be harmful, but I think in the big picture, if are talking "top off water" then a little NH3 would be diluted so much then metabolized by the bacteria rather quickly. water changes might be different but if you have high ammonia you can always treat for it just before you mix your salt.

but this has gone way off the rails of ReefOcean's original question about if the Aqua Pure units are good, there all the same, only difference is amount of stages, type of membrain, and the filters. Do you have a link to a picture of the one your using. Also you need to know a bit about your water, in victoria we had a huge algae content in our water, this sucks as it plugs filters real fast, same if you have high sediment content.

now from what I remember (26 years ago), edmenton had medium hardness water. ok so I just looked, the average TDS seams to run between 138 and 170ppm this time of year and they adjust PH to 7.8

if your talking this aquapure company http://www.aquapure.com/aq-products/...ro5500-lf.html

run away and don't look back, propriatary filters that are expensive.

this is the look the system should have http://www.costco.ca//.product.10344...ontent=Default

I prefer the clear housings myself. most systems like this one (5 stage ro) are comming with a 5micron prefilter, followed by 2 carbon block filters (thats the 3 on the bottom) then the ro AND A gac post filtration. if you are using it for your tank only then you don't need the tank or GAC stage but the GAC won't hurt anything. mine was basicly this but it had two RO membrans for 320 gal per day and a resin filter instead of the GAC. what I did was add a stage at the beginning which was my 25 to 1 graduated filter, put a 1 micron in the chamber that had the 5 in it and then the two carbon blocks.

any questions feel free to ask, sorry for side tracking this thread off topic so bad haha.

Steve

[NIVLEM09]

Don't mean to high jack this thread but I need some advice.im currently using an API Tap water filter and in the process of purchasing an RO/DI unit,which one do you think is the best and what accessories do I need?im such a noob-apologize to the OP

[Craigdillman]

Best to start your own thread,

[Aquattro]

Originally Posted by NIVLEM09

Don't mean to high jack this thread

Then I don't understand. You did. Please start your own, they're free