Here is my 2 cents on this topic. I have been interested in this over the years and studied what results others were getting. A point that comes up again and again, is that you want to prevent dosing the left over fertilizer into the tank if possible. In Dana's thread on this, he noted that his particular phyto of choice was running out of phosphate during the growth phase. So other nutrients would be left over in excess after the phosphate was consumed by the phyto. In this example, phosphate is limiting, but other phytos may consume nutrients in differing ratios and have a different combination of leftover nutrients.
The normal way of removing the leftover fertilizer is to 'wash' the phyto and separate the phyto from the culture fertilizer. This involves processes and equipment not available to the average hobbyist.
To reduce the impact of dosing possibly leftover nutrients, one approach is to condense the phyto to allow the most phyto to be dosed with the least amount of leftover fertilizer nutrients. A way of accomplishing this is to take advantage of the fact that phyto will settle and condense when cooled. Placing a container of phyto in a fridge will result in the phyto settling into a condensed layer in the lower portion of the container. Dosing from the container, drawing from the condensed phyto, will allow a higher ratio of phyto to culture solution to be dosed. As an example, using a 1L culture container, you could dose most of the phyto, while only dosing 250 ml of the solution.
This approach works best when used in a fish room and a small fridge can be utilized for holding the phyto, a dosing pump along with a injection loop. Where other additives require refrigeration, they can also be included in this type of setup. For additives that require periodic mixing, their reservoir can be placed on magnetic mixers, etc.
For those where everything has to fit inside a stand, a single bottle wine cooler may be able to be utilized to cool and condense the phyto (though I have not tried this, so YMMV).
Anyway I think that dosing live phyto both as a means of nutrient control and feeding the zooplankton in the water column is a worthy idea to explore.
Dennis
