Best color to inhibit algae growth?

[Meggy]

I am upgrading my canal water filter. I was using a clear transparent really useful box painted black on 5 sides. One side is left clear as I want to monitor what's happening. The box is situated in a dark corner. That seems satisfactory for inhibiting algae growth. But for aesthetic reasons I'd like to replace it with a colored transparent box. Does anybody know what color is best for inhibiting algae growth?

[Simon Howes]

How about a couple of bacterialcidal uv leds on the inside?

On 9 Aug 2016 5:50 pm, "Meggy" <megt...@gmail.com> wrote:

I am upgrading my canal water filter. I was using a clear transparent really useful box painted black on 5 sides. One side is left clear as I want to monitor what's happening. The box is situated in a dark corner. That seems satisfactory for inhibiting algae growth. But for aesthetic reasons I'd like to replace it with a colored transparent box. Does anybody know what color is best for inhibiting algae growth?

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[Dave Mansfield]

Interesting question.

I'd assume blue, or dark red.

https://www.google.co.uk/search?q=chlorophyll+absorption+spectra&source=lnms&tbm=isch

On Wednesday, 10 August 2016 08:21:27 UTC+1, AbbyKatt wrote:

How about a couple of bacterialcidal uv leds on the inside?

On 9 Aug 2016 5:50 pm, "Meggy" <megt...@gmail.com> wrote:

I am upgrading my canal water filter. I was using a clear transparent really useful box painted black on 5 sides. One side is left clear as I want to monitor what's happening. The box is situated in a dark corner. That seems satisfactory for inhibiting algae growth. But for aesthetic reasons I'd like to replace it with a colored transparent box. Does anybody know what color is best for inhibiting algae growth?

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[A S]

On the contrary, blue and red will let the light through to be photosynthesised; green will inhibit growth the best as the algae will reflect that light back instead of absorbing it. Hence the green colour of algae.

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[Meg Lee Chin]

Thanks! This is all very useful.

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[Meggy]

I bought and installed a green box. But then I came across this article which claims that far from preventing algae growth, green and yellow light will actually encourage it...

https://orphek.com/10-tips-stop-nuisance-algae-

The lights used in the article look like those blacklights used by hippies for psychedelic posters in the 70s. That being the case what does everybody reckon is the best colored box to prevent algae growth?

Im thinking purple?

Here is a list of colors available;

• transparent red
• transparent orange
• transparent yellow
• transparent bright lime
• transparent green
• transparent aqua
• transparent blue
• transparent bright blue
• transparent pink
• transparent bright pink
• transparent purple
• transparent smoke

http://www.reallyusefulproducts.co.uk/uk/html/colours.php

[Adrian Godwin]

I would have said red or purple, thinking green was important, but Ariel's right, it does mean that the plant reflects it rather than absorbs it.

In general, you want to block UV to inhibit plant growth. But underwater plants are different : they won't get much UV, and what light they do get will be mostly green or blue. So I'd expect them to be optimised for that. If they want shorter wavelengths and reflect green, it implies that they absorb blue, so that's probably what you want to block. So use a red filter : the plant presumably doesn't care much about green light and the red filter will block the blue light.

[Dirk-Willem van Gulik]

On 19 Aug 2016, at 10:34, Meggy <megt...@gmail.com> wrote:

I bought and installed a green box. But then I came across this article which claims that far from preventing algae growth, green and yellow light will actually encourage it...

https://orphek.com/10-tips-stop-nuisance-algae-

The lights used in the article look like those blacklights used by hippies for psychedelic posters in the 70s. That being the case what does everybody reckon is the best colored box to prevent algae growth?

Im thinking purple?

So the issue is that algae have evolved in normal water - which lets light through:

http://www.oceansjsu.com/105d/exped_briny/13.html

Even to fair depths. 

So high up - green algae do well and as we go deeper brown and blue algae start to win. 

But ultimately there are algae for just about any part of the spectrum and thus it is a battle hard to win (though anti algae a chemicals can be very effective (and incredible smelly)). 

If black is no option - green algae tend to need the most light (generally evolved high in the water column). So overall reducing of light level and sharp filtering for the non green ones (that florish on a lot less) may help. 

Dw. 

[Dirk-Willem van Gulik]

On 19 Aug 2016, at 13:54, Adrian Godwin <artg...@gmail.com> wrote:

I would have said red or purple, thinking green was important, but Ariel's right, it does mean that the plant reflects it rather than absorbs it.

In general, you want to block UV to inhibit plant growth. But underwater plants are different : they won't get much UV, and what light they do get will be mostly green or blue. So I'd expect them to be optimised for that. If they want shorter wavelengths and reflect green, it implies that they absorb blue, so that's probably what you want to block. So use a red filter : the plant presumably doesn't care much about green light and the red filter will block the blue light.

A search for algae absorbtion spectrum should give you an idea. Also note that just 2 or three families of algae together can feast on just about any part of the spectrum - including ranges not present in solar light. 

Dw. 

http://www.ibiblio.org/virtualcell/amazingbiology/oceanography/2A4.htm

http://journal.hep.com.cn/fesci/EN/10.1007/s11707-013-0373-z

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[Edward Emanuel]

Hi Maggie,
If it helps pipes and tanks used in most aquaculture systems are glossed, coloured or covered and not transparent or semi transparent so as to inhibit algal growth. I would avoid any translucent or transparent material, paint it with black gloss to be sure. Bear in mind that autotrophic bacteria and algae can proliferate without light in canal systems so inhibiting photosynthesis may not stop growth completely. Mechanical cleaning and sensible light restricting precautions are the only way to avoid algal growth, of course you can add chloramine or other growth inhibitors (be careful with UV as it may back fire!), with some restrictions on flow back such as a valve or trap.
Good luck,
Edward Emanuel BSc (Marine Biology)

[Meg Lee Chin]

Im thinking I may as well just stick with the green transparent box seeing as I've already spent the £18 and cuts holes in it. I suppose I can just attach a black curtain it with velcro and simply remove it for inspection.

However my mate Crazy Nick suggested that for a laugh I might as well experiment with other ways of inhibiting algae such as:

Applying a small voltage through the box
Adding a silver or copper coin or other substance

Any ideas?

Keep in mind that although I dont use my canal water filter for drinking I do use it for washing up and showering. Also electricity is limited on my boat.

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[Dirk-Willem van Gulik]

On 20 Aug 2016, at 10:51, Meg Lee Chin <megt...@gmail.com> wrote:

Im thinking I may as well just stick with the green transparent box seeing as I've already spent the £18 and cuts holes in it. I suppose I can just attach a black curtain it with velcro and simply remove it for inspection.

However my mate Crazy Nick suggested that for a laugh I might as well experiment with other ways of inhibiting algae such as:

Applying a small voltage through the box
Adding a silver or copper coin or other substance

Any ideas?

Keep in mind that although I dont use my canal water filter for drinking I do use it for washing up and showering. Also electricity is limited on my boat.

Given that you are on a boat, a tiny tiny smidgen from the biocide you put in the diesel tank will do wonders and likely last for years in a plastic tank. 

Dw. 

On 19 August 2016 at 17:58, Edward Emanuel <ecpem...@gmail.com> wrote:

Hi Maggie,
If it helps pipes and tanks used in most aquaculture systems are glossed, coloured or covered and not transparent or semi transparent so as to inhibit algal growth. I would avoid any translucent or transparent material, paint it with black gloss to be sure. Bear in mind that autotrophic bacteria and algae can proliferate without light in canal systems so inhibiting photosynthesis may not stop growth completely. Mechanical cleaning and sensible light restricting precautions are the only way to avoid algal growth, of course you can add chloramine or other growth inhibitors (be careful with UV as it may back fire!), with some restrictions on flow back such as a valve or trap.
Good luck,
Edward Emanuel BSc (Marine Biology)

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[A S]

Have you considered bubbling some ozone through it? I found http://www.ebay.co.uk/itm/like/141679778702 with a quick search, but you can probably pick up something smaller and cheaper than that.
Not sure how much ventilation you have though.

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