JBL AquaCristal UV-C: Does the ultraviolet light destroy active ingredients of my aquatic plant fertiliser?

UVC light degrades the chelators in the fertilizers, which prevent the precipitation of trace elements such as iron, among others. Therefore, when using a UVC water clarifier, it is advisable to change over to daily fertilisation. The standard dose needs to be converted into a daily dose at the beginning. It may also be necessary to increase the fertiliser dose slightly. Iron should be detectable in traces at least prior to each subsequent application of fertiliser. Vitamins and other higher grade organic compounds may likewise be broken down. Therefore, when using vitamins, it is advisable to add the fertilizer with the food twice a week.

I would like to fertilise my plants with your product and change over completely. How do I go about doing that?
Generally, one should never change plant fertilizers abruptly. The fertilizers from different manufacturers have somewhat different compositions in terms of trace elements. This may cause temporary nutrient changes. It is best to change over in 3 steps:

1) Reduction of the old fertilizer by 1/3; replace this with 1/3 of the new fertilizer. Wait approx. 3-4 weeks and observe the reaction of the plants.

2) Reduction of the old fertilizer by 2/3; replace this with 2/3 of the new fertilizer. Wait approx. 3-4 weeks and observe the reaction of the plants.

3) Complete discontinuation of the old fertilizer and change-over to the new fertilizer.

It is important to observe the reaction of plant growth and, in addition, to check the iron content of the water at least 2x weekly. Whereas the value should never drop to 0, it should never exceed 0.2 mg/l if possible. However, short peaks are no cause for concern.

These measures should generally be carried out on a weekly basis, ideally right after a water change. This achieves better results than fertilizing in large doses at longer intervals.