Hoppy,
This is where I get confused. I can buy that a nutrient doesn't cause algae. However, in smp's case, after he reduced the phosphates in his water, the algae went away. Why is this?
Also, when I tried to add phosphates in my tank, algae increased. Currently, I am using a combined method of Chuck Gaad's calculator for and a phosphorus test to determine the amount of N&K to add. Between the amount of fish food and water supply, I feel I have more than enough phosphorus and do not add it at this point.
As a result, the algae is disappearing. In addition, the plants are growing nicely. So why does the addition of phosphorus seem to coincide with algae growth in many instances?
Because there are such things as indirect effects.
Not everything is a simple add this= this effect.
If you had poor CO2, limiting PO4 reduces the CO2 demand of the plants(not algae), so you end up with with stronger PO4 limitation than CO2 limitation.
PMDD folks believed it was PO4 limitation that was the key to algae. clearly, it was not the case, but indirect effects led many to think so.
If you tested things the right way and the careful way, you'd see that CO2, not limiting PO4, was the issue in the experimental design.
Going back and making sure CO2 was good, now we can add both high or lower PO4 and have the same outcome without algae. If fact, lower PO4 will lead to more algae over time where CO2 is non limiting.
Also, the limitations are not these simple on/off toggle switches, they are continuous and go from strong to moderate to mild to non limiting etc.
This applies to light, to CO2 certainly.
You can use concentration in the water on the lower X axis also and O2 gas evolution on the Y axis if you so chose, the shape and response is the same.
Have you spent much time testing and measuring light?
If you want to manage CO2 better, and cannot control it effectively, reduction in lighting is a better approach, you will get less algae and if you seek to also use limiting PO4, this method will work even better
roud:
Less light= less PO4 demand and less CO2 demand.
Also,
good CO2 use is the bane of many planted hobbyist.
So careful, patient, adjustments, observations, good flow and routine cleaning of the filters, current adjustment, light is wise to master CO2.
Many aquarist are not patient. They rush, gas their fish, do not wait, expect immediate results, add too much excess light.
Twain said:
"It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so."
So confirm if the PO4 test is accurate before running off messing with managing the PO4 with removers, water changes and dosing adjustments.
CO2 is much harder to manage than any nutrient. Light is the most stable, and correlation does not imply cause, nor are causes a factor of a (one or many) direct relationship/s. so many frustrated with their own issues with poor CO2, stumble on PO4 limitation to better stabilize CO2 indirectly.
But then you live with GSA and waste a good amount of the light energy to get the same rates of growth, and if you dose any PO4, then issues come about.
There's a trade off certainly.
But if it's about better in control of all things, then CO2 is the one to really master along with light, nutrients are much easier thereafter and you have less dependencies and can see what is really occurring.
You cannot test anything if you have other dependent variables going on you assume are not present.
Regards,
Tom Barr
