Hot Tips: Water Purification Tips

by | Jun 15, 2005 | 0 comments

A selection of useful tidbits of information and tricks for the marine aquarist submitted by Advanced Aquarist’s readership. Readers are encouraged to post them to our Hot Tips sticky in the General Reefkeeping Discussion forum or send their tips to [email protected] for possible publication. Next month’s Hot Tip theme will be “Online Purchasing Tips“.


Water Purification Tips:

Add a DI to your RO unit. Even with 1-2 TDS coming out of the RO you can still have all sorts of undesireables making it through.


Get the highest gpd unit you can afford. More gpd means more RO membrane. More membrane means longer life for the filter.


Clean your water storage containers with a water/bleach mixture. Rinse well with freshwater and allow them to dry completely before refilling with purified water. There isn’t much point in putting RO/DI water with a zero TDS reading in a container that isn’t completely clean.


Don’t get an RO membrane rated for more than 75gpd for household use. The pore size on those membranes is too large and it lets too many contaminants through.

Use a pressure gauge to check your sediment and carbon filters for clogging. If the carbon isn’t working the chlorine will destroy your RO membrane.

Never add the solids in limewater to the tank, that’s where any residual heavy metals will end up. This also means that limewater will remove heavy metals when used properly.

Get a good TDS meter for your RO/DI water and use it!


When setting up a new and large tank (100g+?) use a household point of use filter (Pur, Brita) to filter the water. Add your mix, live rock (to cure) and run carbon, and a PO4 remover 24/7 untill cycled. Water ends up as good as RO and you didn’t have to wait 8 days while your RO filter made 320 gallons of water.

Rob Top

I use two sediment filters and a tfc membrane rated for 125gpd. Get clear canisters so you have a visual of the sediment filters as they age. Locate a good place to stock up on filters and do so. I usually buy a years worth of filters at a time.

Clean you storage tanks and if you have a separate salt tank you need to have a powerhead in the tank to stir the water. Set it up on a timer and run it twice a day for 25mins.

Always use a shut off device.


Buy a ro/di unit that comes with a pressure gauge and tds meter.




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