[APD] Re: Siesta to prevent algae?

["Michi Henning" <michi at zeroc_com>]

> From: Thomas  Barr <tcbiii at earthlink_net>
>
> >I just bought a German book published by Dennerle. (As
> >far as I know, an English version is not available.) The title
> >translates as "System for Fascinating Aquariums".
>
> I gave a critique of their suggestions on APD, and AQ.
> A rather blistering critque...
> It was from their Englisg version site.
> You can look it up on those forums.

Thanks for your comments Tom! Would you have a link to this
info? I tried a search, but couldn't find it -- the search function on
the digest pages isn't terribly selective. BTW, at least some of
the info on algae in this book seems to be quite good. (At least,
they preach the same thing that you do: look after the plants,
and the algae will look after themselves.)

> >"Our recommendation [to reduce algae growth]:
>  >Reduce the lighting duration from 12 to 10, 9, or 8 hours. Or,
>  >even better, allow your plants and fish a `siesta'. The following
>  >rhythm has proven itself: 4-5 hours light in the morning, then a
>  >a dark period of 2-4 hours, followed by 4-7 hours of light.
>
> Well, my suggestion is to improve the plant growth.
> Algae and plants both have choloroplast, why would this do anything?

Yes, my thought too.

> I think what is occuring is that the CO2 is mildly insufficent. Turning
off the lights stops the CO2 uptake.
> This gives the CO2 system and chance to catch up.

In my case, I don't think that would apply. I have the CO2 on a pH
monitor, so it never leaves the range 6.70-6.80, at a KH of 4.5,
which works out to about 20-30ppm CO2.

> Unless they do a control and make sure other parameter are independent the
lighting, how will you know?
> I suppose just try it and see but you need to be sure that the light in
and of itself is the causative variable.

I'm doing this at the moment. Not so much to try and reduce algae, but
to reduce light overall. My new tank has been set up for three weeks now.
Things are going extremely well, not a trace of algae on the plants. But
I am getting a small amount of very thin hair algae growing on stones
and the background (pieces of Indian slate glued to the back pane).
I'm looking for ideas for how to deal with that. It's not threatening at
the moment, just annoying -- there is a thin coating (maybe 3-4mm
in length) on the background. The algae threads are extremely thin
(less than 1/10 mm in diameter). It looks a bit like a coating of green
velvet.

I'm dosing traces daily, and NO3 and PO4 every second day. (Especially
PO4 seems to disappear about as quickly as I pour it in, from 0.5ppm to
nearly zero within 48 hours.) I have twenty Otocinclus Affinis in the tank
(130gal), two bristlenoses, and two Rinelocaria sp. "red", to help with
the cleanup. They are all eating, but I think the algae are still outgrowing
what they can consume. Interestingly, the three pieces of driftwood in
the tank do not show any algae growth. I find the algae only on the stones
and, to a lesser extent, on the glass.

At the moment, my thinking is that I have to reduce light to get rid of that
algae. (I'm using two 150W metal halides plus two 36W fluoros. The
halides are Osram WDL, and the flouros are Osram 840.) But I'd be
keen to get suggestions as to what else I could try.

> > "Contrary to popular opinion, we have not noticed any
> > negative effects of this lighting rhythm on either fish or plants -- 
> >  presumably
> > because significant light reduction is frequent in the tropics, for
example
> > due to thunderstorms."
>
> And algae are also sujected to this same environment!
> We have algae in the northern regions, in deserts, etc, they still grow, I
don't buy the tropics thunderstorm arguement for a second.
>
> > "Algae obviously dislike the `siesta'."
>
> It's not so obvious to me.

No, it's not obvious to me either.

> If a peroid of dark helps, then a blackout will do the most harm to algae
vs plants.
> Generally less light is better also.
> This also places less demand on CO2 supply.

What would be the minimum lighting period that could be used
before the plants would seriously suffer? I know that Kasselmann
suggest that the absolute minimum is 8-9 hours. I'm down to 9 hours
now, and I'm still getting that green hair algae. Should I reduce light
further? Or am I overdosing on traces? (I'm using Duplaplant 24
daily, ten drops into 130gal.)

Cheers,

Michi.
--
Michi Henning              Ph: +61 4 1118-2700
ZeroC, Inc.                http://www.zeroc.com


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