Yes, it is lost from the water column due to photodegradation of the EDTA followed by precipitation of the Fe+3 (after oxidation from Fe+2). It's stilll in the aquarium - most likely in the gravel and filter.
The effect is most pronounced with wavelengths less than 400nm (UV) - thus the suggestion that a UV sterilizer not be run 24/7.
Fe+3 is a stronger chelator than some of the other trace elements needed by plants (like Co+2), so there is also a domino effect where the Fe+3 can "steal" an EDTA from a cobalt ion.
This paper: Laan et al, Environ. Chem. 2004, 1, 107-115. proposes a possible photostable, iron-binding-specific alternative to EDTA: desferrioxamine B. They showed that the compound is not photodegraded, but did not investigate the toxicity of DFO-B or its effect on the availability of the iron for plants (though they imply the data is being collected).
72g bowfront planted, CO2, 4x - T5HO, Eheim 2213 and 2217, 2 angels, pristella tetras, blue tetras, betta, albino bristlenose pleco, albino cories. Sword, vals, hygros, ludwigias, java moss and fern, anubias
2g Mac-quarium. Clown gravel, fluorescent plastic plants, and 2 guppies.