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Re:PO4 Deficiency & CO2 Swing

> Thomas Barr wrote:
>> 
>> If you see dramatic pearling after about an hour or so you likely where
> PO4
>> limited.
>> Good job with the yeast BTW. It's not easy to keep the CO2 up like that.
> 
> The thing is, this is the first time that the CO2 concentration has been
> that high and that constant with little output. I used get less than 15 ppm
> by the end of the day. One thing I didn't mention was that my NO3 also
> climbed pretty high with regular additions, meaning plants were not
> consuming it (as fast). When I added that pinch of PO4, the NO3 dropped to 0
> in 2-3 days.

It takes a balance of things not just one. Glad you figured it out:) Running
the nutrients down for a day or so is okay for the macro's and up to a
couple of weeks for the micro's in some cases. I try to add P and N from
fish food( a light amount of N and P additions with some NH4/NO3 mixed in)
and add these every other day or every 3rd day(2-3 x a week). 5.0ppm max on
the NO3 and about 1ppm on the PO4 for each addition.
> 
>> Sure but after you go in and attack all the algae first manually. Then the
>> proverbial water change(I like 50%) and then you add your nutrient mix
> back
>> in. You can add by estimation easily by doing the 50% water change and
>> assuming that there are no nutrients in there besides GH(Ca, Mg).
>> Repeat this 3 times over 3 weeks or maybe once or twice extra in between
>> refilling your nutrients each time. Don't forget CO2 during this time.
>> Try adding a bit more micro's and note the algae response. Try .2ppm then
>> try .5ppm. See what you get. Same with the PO4 when you get a kit.Not
> quite
>> sure an optimal range is for PO4 just not too low or extremely high(above
>> 1.5ppm...I guess)
> 
> What is the purpose of the 3 water changes and nutrient refills?

"Resets" the tank and gets rid of any excess and build up mistakes that
you've made during the week. Keeps the levels even and stable in your tank.
Good chance to harass algae and algae don't like water changes/healthy
plants that have access to good nutrient levels. If you keep up on that the
algae will be in trouble and your plants will be quite happy. It's work but
reduces errors that we make.

>I was
> thinking of just adding PO4 when I see signs of slow growth. Do you think
> that a measurable amount of PO4 does more against the algae than an
> immeasurable one?

Certainly.

> Also, is more than 0.1 ppm iron needed in tanks with high
> lighting?

Ditto, certainly. But it all revolves around having a good CO2 supply and
good maintenance. You mess with that and nothing is going to work very well.
That's why I nag that issue. It solves much of the problem. But then gets
you into nutrition additions like P, N, Fe etc. It all just revolves around
the Light, CO2, and nutrient issue. Grow faster, use more, at least up to a
point.
Regards, 
Tom Barr
> ___
> Alex R.
> pcalex at yahoo_com