Electric

May I assume that you don't want *anything* growing in your water not just a lack of algae? The reason I ask is because you *will* have things growing in your water even if it is in total darkness.

But it's bad for the fish ;-)

I use RO water, with salt added, for my salt water fish tank.

Due to the large amount of sunlight coming thru my 12' x 15' great room window I have to clean every other week to keep the algae from becoming visible.

...Jim Thompson

Indeed, it sounds like some experimentation is in order. Grab a handful of the various color LEDs and see which ones "grow" algae the best.

-- Kzizz to Ikzik: "Hey Ik... didn't we pass that barn an hour ago? YOU IDIOT, WE'RE FLYING IN CROP CIRCLES!!!"

The chlorophyll in plants can absorb useful energy from red and blue wavelengths. If your LEDs produce light in either or both of these absorption bands, they may support the growth of algae.

AFAIK, seals prefer salt water. The fresh water irritates their eyes. (Sorry, I couldn't resist.)

Seriously, though, many years ago, a French scientist by the name of Pasteur showed very convincingly that life cannot be created from inanimate matter. Since then, all scientists (AFAIK) have believed this to be true. So I don't think that LED's can create living algae in distilled (and therefore sterile) water.

Also, algae (and other photosynthetic aquatic organisms) need minerals to grow, not just water, air, and light.

Personally, my experience has been that the best way to inhibit algae growth in water which already contains algae is to do both of the following:

Number 2) works OK by itself, too.

However, it sounds as though your water will have a much lower (possibly zero) algae concentration than mine to begin with. Given that, I doubt very much that a few LED's will lead to much algae growth just because the overall intensity of light will be low, but I don't know what wavelengths algae are most sensitive to.

If you really need to know, I suggest you find a scientific forum dedicated to aquatic life (or microorganisms) and repost your questions there.

--Mac

Well, sterile water won't have anything growing in it, even if it is in full tropical sunshine. It's all about how carefully sterility is maintained. The OP didn't claim sterility, but if it is distilled, it should be close.

Also, if there is close to zero mineral and organic content in the water (which should be the case for distilled water) then any organisms which do find their way into the water will be nutrient-limited and will not increase much in numbers.

--Mac

I read in sci.electronics.design that Mac wrote (in ) about 'Electric', on Sun, 16 Jan 2005:

We just had a thread here with reports of stuff growing in ultra-pure water (not to mention the mercuric chloride solution!).

No, Algae has to be already present through some kind of contamination.

I would think the frequency of the light needs to be suitable for photosynthesis in order to foster any kind of plant growth.

Distilled water has high electrical resistence adding anything such as chlorine bleach to the water will destroy this resistance. But if that resistance is unimportant I would recommend putting three drops of Chlorox at full strength to one gallon of water given each drop is 1/20 of a ml. I think it is impossible for a common person to avoid contamination of distilled water when making anything so if you are worried about the growth of stuff you will need that chlorine added. Unless of course the project will operate for only a short time. I understand in a closed system like a nuclear reactor strange chemicals will spontainiously appear to contaminate the primary system just from radiation alone.

I'm Not an expert, gmv

There is a good reason why so many thought that life *can* be created from inanimate matter; it is almost impossible to keep that first living thing out of a system, thus making it appear as if life can be created from inanimate matter

If you have ever worked with ultrapure water systems you will have experienced opening up a system that is supposed to be pure H2O and having black or green ooze come out instead.

Good luck keeping *all* minerals away from the little buggies. I have seen filamentary bacteria growing in distilled water in a sealed polypropylene container.

"Close" applies to hand grenades, horeshoes, and atomic bombs. "Close" inn't good enough to maintain sterility.

I suggest that you get some distilled water, expose it to ordinrary air, and wait a few months. Do that and your opinion about how well limiting mineral and organic content in the water works to supress bacterial growth will no doubt change. It sounds great in theory but in the real world you get slimed.

In that thread we had a poster who refused to believe that ultrapure water won't stay ultrapure when exposed to the internals of typical electrical equipment. What ever happed to "do the experiment yourself and see what happens?" A jug of distilled water from the supermaket poured into a stainless steel bowl and covered with a loos-fitting lid will show the folly of thinking that the bugs won't grow.

Obviously, it can't be considered sterile or even distilled, really, if it is exposed to air for a few months. Dust motes and biological spores in the millions will accumulate in such water. At which point, it will certainly support growth of some kind.

As I said, it is all about how carefully sterility is maintained.

And the OP did contain the word "seal," so there is some possibility that the water is protected from exposure to ordinary air.

--Mac

The "flapper" on the toilet was leaking, so I replaced it today... it had just been cleaned just a few months ago. Should I have been surprised that there was a white film on the top of the water in there, and white slime on the old flapper? This is dispite the relatively high levels of fluorine and chlorine in the water... still, life will find a way.

That's why astronomers and cosmologists are so excited about bodies with liquid water on them - wherever we see water, we see life.

You know, I might just do this. I'll buy some distilled water from the store, boil it, let it cool in the pot with the top still on, then open it for 5 minutes and transfer to a mason jar and cover it with cellophane and let it sit for 90 days to see what happens.

I'll rinse the mason jar out with tap water before I start. Then I'll rinse it again a three times with the boiled distilled water before I add the final batch of distilled water.

I'll leave the covered mason jar on a counter in my kitchen.

After 90 days, I don't expect obvious signs of growth.

Who knows what the point was of the OP.