Guys I am using ro water (from supermarket) for top offs and would like to switch to store brand water because its cheaper. The label says "conforms to all existing federal, state, and local standards for bottled water purity". Does this mean Reverse osmosis and/or distilled?? and is it safe to use without chems? Thanks dudes!!

Bottled water purity is great for human consumption but not for a marine tank.

The 2 things that totally contribute to and fuel nuisance algae in a tank are excess feeding and high TDS(total dissolved solids) water. Distillation and reverse osmosis just doesn't cut it when trying to achieve a TDS of zero.

My tap water has a TDS of about 70. The measurement after sediment, carbon and r/o still reads about 3-5 TDS. Only after going through the first DI (deionization) cartridge does it finally measure 0 TDS.

An Ro/di filter should be the first piece of hardware purchased for any marine tank, 2nd should be a good skimmer.

A lot of people end up giving up the hobby due to hair algae that they can't get rid of. RO/DI water is not a cure all but it does take a big problem out of the equation.

Pick up a cheap $15-$25 TDS meter and check the RO and distilled water you are using. You will be surprised.

Nope. The Chlorine and Chloramine have been removed by the RO process.

RO water is much better than straight tap and there is no benefit with using water conditioners at this point.

The only thing lacking after good RO water is good RO that has run through DI resin.

If you're just using tap water, by all means, keep using the water conditioners until you get an RO/DI.

good info man.............i am useing RO water from wally world right now.....my hair algae is at a minimum but still shows it's ugly head now and again ....but not the lush green lawn it used to be by any means, algae hermit crabs have made a huge difference in my algae control -almost non exsistant.....................wal-marts "always" brand water comes in two types....green label is UV filtered and the blue label is RO {not Deionized} and they are both 66 cents a gallon.......Serieal32 and I found a Culigan dispenser at a different walmart and we pay 1.97 for 5 gallons of RO {again not DI} water {the first bottle is 15 bucks but then you own the container and refills are cheap......we take turns every other week or so and get 30 galons for the tanks in the house} @ 11.82 per week...................it's livable for now......glad to hear about the RO/DI vs. just RO......no one has been able to explain it to me until now.........so now the house RO unit will get a DI unit as well when it goes in......thanks SCHIGARA....................Boss

i have a question about RO/DI filters it may be different for me since i am freshwater, but since a RO unit only filters 75- 150 gallons a day where does it fit into you filtration system is it filtered directly into your tank, inline with your other filters, i use a canister filter. Or is it strictly for say a resivior tank. Not keep in mind i am a freshwater guy and really have no clue about how saltwater is set up but i figured since you were talking about it i would ask a few.

got it