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2,069 Posts
I've never suggested RO is ever needed except in two cases out of perhaps several thousand.
They had private wells, one with copper pipes and had 2ppm of Cu, the other had salt water intrusion on their well.

Other wise it's redundant to take something out of the water only to add it back again, on a practical level this is simply never needed except in exceedingly rare cases.

I guess if you enjoy making more work for yourself, providing a reservoir for your water changes, only have a few/one small tank/s etc, it's no biggie.
Initial cost is an issue for many folks, I'd just get a CO2 tank/system, that's cheaper than RO over time.

I do not know what "bad tap water" is for a planted tank.
I've had tap water from 20ppm KH to 320ppm, GH's from 30ppm to 450ppm.

Plants tend to do better in the harder waters. You can see this in nature as well as in the tanks. RO taste good, I like them for drinking water, but not my tanks. I like to make the water change easy, then I have less to deal with.
I can change it fast, easy, adjust the temp easily etc.

For many years it was said that plants prefer soft acid water, that we needed RO water, that's simply not true.

Some fish may prefer less KH/GH, this is debatable depending on the species, loaches will be quite fine for decades in harder waters(I can show you some 14" ones living in good hard tap water)

Save your RO water for the Reef and drinking.
Otherwise you are taking the GH/KH out and then adding back, that's not needed.

What precisely in tap water that might be in excess would be "bad" or otherwise undesirable season to season? Taking a KH reading once in while would solve any of that. Even if that did vary, the amount of CO2 being added is stable unless the system has a pH controller, which is one reason I never use one nor tell others to use them.
Plants will use the same amount of CO2 at 2KH as they do at 4. The rate of CO2 additions is also the same, so I fail to see how the variation woukld be bad unless you did not have "enough", adding a little bit after each water change for GH solves that if there is little GH in the tap.

Seems like lots of work to remove something and then add it back and no gain for the work. What do you gain from that?

Tank's growth, plant density, plant species, lighting, dosing, etc change each week, month, year, how do account for all those variables? I suppose you can test and test and test and then test your test kits as well and spend the $ there.

Seems testing the KH once in awhile and using tap is a much easier way to go and much cheaper, don't forget about all the waste water(90% rejection rate for an average) and pumping cost associated with that well water.

I've never had any assoicated problems with a wide range of tap waters, neither has the entire SFBAAPS group for the last 9 years, we live where there are large variations in local tap water types. It's easy to compare.

Regarding the algae: you will not beat algae by using RO water on a plant tank, it's just that simple. Grow the plants and focus on their needs, for a 75 gal, it's fairly easy, tell me what your GH and KH are, I can pretty much give you an easy routine that requires very little testing except of pH/KH.

Then you can work on the reef tank(Use an refugium BTW) and use the RO for that if you want. Call your tap water companyb up also and see what levels they send for NO3/PO4/GH/KH and their ranges also.

Tom Barr

2,069 Posts
One thing that really makes a smaller reef tank run well: largen water changes, 1-2 weeks, 50-70% even.
No testing, not dosing etc.alt cost, but so do all those supp's and a PITA.
It becomes cost effective on larger tanks but even 100-150 gal tanks are still quite reasonable with SPS and Macro algae etc.

Are you looking for a non PO4 due to the reef?
Amquel works well for both, but there's no need to worry about PO4 in a FW planted tank, adding will reduce algae and make the plants grow better.
Adding PO4 to reef will cause diatom blooms on the glass and sometimes of the corals and rock.

Lake MI water is fairly decent.
Save your RO for the Reef and the drinking.

Here's a cheap simple method for the 75 gal tank:
50% weekly w/c.
Add 3x a week: 1/2 teaspoon of KNO3
/18 teaspoon of KH2PO4
Add 15mls of trace mix(Flourish etc) 3x a week

That's it.

You add 3 things.
Like feeding your fish every day etc.

You can scale this down to the 29 gal as well.

Add enough CO2 to get 30ppm during the day(you can leave it off at night since plants do not use CO2 at night except for one genus of aquatic CAM plants).
Measure the KH, see what pH you need to acheive the CO2 level based on the pH/KH/CO2 table, add enough CO2 to drive down the pH to this level. Do not use anything else to change the pH, it's CO2 you and it's CO2 you should add.

pH stablilty etc plays no role in fish health/tank stability or plant growth at night when using CO2 gas.

Tom Barr
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