# Algae elimination with RO/DI water



## mmfish (Dec 24, 2008)

The most effective treatment thus far in a planted tank, with shrimp only, co2, and fertilizer dosing, T-5 lighting, to reduce algae, has been RO/DI water. I add sea-chem equilibrium, which is needed to add back extracted materials other than tap water phosphates. Any others have similar results?


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## KentCurtis (Jan 22, 2009)

I have been considering switching to RO/DI water just to completely avoid any guesswork and testing. Maybe I am completely wrong here, but is RO/DI water basically 100% pure? Like, GH and KH of zero, Zeros across the board?


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## bsmith (Jan 8, 2007)

Depending on the cost of the unit any where from 98%-99.99% pure.



KentCurtis said:


> I have been considering switching to RO/DI water just to completely avoid any guesswork and testing. Maybe I am completely wrong here, but is RO/DI water basically 100% pure? Like, GH and KH of zero, Zeros across the board?


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## plantbrain (Dec 15, 2003)

I do not have any such issues do not use RO.
I have no algae issues unless they are CO2 related.
Nutrients(at least excess levels) in other words, NO3, PO4 etc, are independent of algae issues.

So you should look elsewhere for the issues, maybe it was higher KH and poor CO2, or some toxicant in the tap(see below). It's not nutrients however from the tap unless it's very high like for Mg or Cu.

I showed this well over a decade ago specifically regarding RO.
Shrimp do seem to like softer KH's, GH is less of an issue.
But you claim is that RO eliminates algae, which is simply not true.

I have had all sort of tap over the last 20 years(hard, soft, with PO4 or none at all), RO did not help me with algae, actually, the reverse was true. 
I used it when I lived in Davis where the Mg was 50ppm or higher, but more for the plants.

It did not induce algae of any sort.

I use tap and have had no algae, so your speculation is not supportable.
Folks that use RO also have algae also:thumbsup:
You should look elsewhere for the claim about algae/RO.

You made some changes, but have not shown it was due to RO water, nor nutrients.

Regards, 
Tom Barr


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## dewalltheway (Jan 19, 2005)

I will back up what Tom said. I use RO/DI water with Equilibrium and I still contend with algea issues. You are correct though that RO/DI water does have a KH & GH of zero but I don't believe it's zero's across the board.


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## plantbrain (Dec 15, 2003)

dewalltheway said:


> I will back up what Tom said. I use RO/DI water with Equilibrium and I still contend with algea issues. You are correct though that RO/DI water does have a KH & GH of zero but I don't believe it's zero's across the board.


Typically KH will slip through more than GH
TDS tells when it's time to change out the Filter.

RO might have save this person, at least they think so.............so the old "whatever works for you" claim is valid.

What is NOT valid is the conclusion.
RO does not eliminate algae.

Correlation does not imply cause. In this hobby, there is a very strong temptation to do so, but t is wrong and not about real learning, Science or logic. You have to fairly test your claim and see if it valid or hold true tentatively. 

If you lack the control to have a tank with RO water and still have algae, it does not imply RO helps or hurts the algae. Likewise, if you use RO and now no longer have algae, it's not that simple.

Many other issue may be occurring, and folks without RO should have algae as well. If some do and some don't have algae that do not use RO, what does that tell you?

It cannot be the RO.
It has to be something else causing algae for that observation to hold true(which we assume it does).

Regards, 
Tom Barr


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## jaidexl (Sep 18, 2006)

dewalltheway said:


> I use RO/DI water with Equilibrium and I still contend with algae issues.


Same here. RO/DI will not save you from algae issues. Nutrients are not a bad thing in planted aquaria, however a lack of them is.


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## BiscuitSlayer (Apr 1, 2005)

jaidexl said:


> Same here. RO/DI will not save you from algae issues. Nutrients are not a bad thing in planted aquaria, however a lack of them is.


X3!

RO/DI is not the magic bullet for avoiding algae.

Tom's comments will get you a lot further.


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## plantbrain (Dec 15, 2003)

I think one of the main issues is when folks switch tap or use RO, they change the KH radically.

This may or may not influence their CO2 method. The CO2 and how it's measured is likely the root for the cause here, not RO water itself. 

Some tap has things that influences KH measurement, leading to poor CO2 measurement. However, it's a CO2 measurement issue, not a nutrient issue in either case.

I think overall, more plants do well/better when CO2 is added at lower KH's.

So that might be why some think this.
Still, all you have to do test the alternative here, add excess nutrients to an otherwise well run tank with good attention paid to CO2, then you do not have algae at high ppm's of K, NO3, PO4, traces, GH etc...............
Even at high or low light.

So it cannot be due to "nutrient excess".
Some other factor is causing the algae issues.

So there's a possible reason why someone might conclude this.
It's an old myth gong way back to the RO filter sales folks pushing the LFS's sales.

Regards, 
Tom Barr


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## wkndracer (Mar 14, 2009)

*R O & algae*

R O solved crappy water quality issues for me but fine fuzz still grows on the leaves in direct light. So no, R O does not eliminate algae. My tanks were filled first with distilled (10 months), building content back, and now with R O and building back. The difference other than price and convenience is the fact that with R O I can do larger changes and stay consistent. Every Saturday I'm adding approx on average of 35grams of Grumpy's GH Booster to raise GH on a 50% water change. Plants looked better by the end of the first week. 

But still have algae growing on the glass and fuzz on the leaves.
TDS reads 178-191 going in and 1 TDS to my holding tank.


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## KentCurtis (Jan 22, 2009)

how do you suggest checking MG levels? My water quality report is here and I dont see it included http://ci.fairborn.oh.us/documents/2008ccrinadobe.pdf . Is that Copper high whatsoever?


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