We have found at our store the Elos Expertline ExtraTrace to work the best at raising your trace elements levels. This product is a European product and because of this the directions are not 100% clear for us in the USA. Here is a simplified set of direction that I hope you will find useful.
Elos Extra Trace, an additive of the EXPERTLINE, is a product specifically design to match the need of all the aquariums containing a high number of corals as well as for aquarium with very efficient filtering, protein skimmer or using very strong lighting systems. Specially dedicated to the advanced marine aquarium enthusiast, it is a very efficient, highly concentrated integrator that contains a balanced quantity of trace elements such as manganese, barium, boron, iron, gold as well as a multitude of other pure salts that are necessary for fishes and invertebrates, sometimes in only very minute quantities.
US Gallon Conversion: Elos Extra Trace may be dosed once or twice a week depending on the amount of shrimp, crustacean and corals you have in your aquarium. Dosing is 3 drops 4 gallons or 15 drops per 20 gallons. Elos Extra Trace is much more concentrated than other trace elements supplements so be very careful when dosing. Since these are trace elements there are no tests available to test these elements.
Metric Dosing: Elos Extra Iodine may be dosed as much as needed to maintain correct levels. Dosing is 1 drop per every 25 Lt of water or 4 drops per 100 Lt.
Ensure that Magnesium and Calcium are within specifications also. When using in a Balling method you will need to figure amount of absorption and adjust amount as needed to maintain correct levels. If using all 6 Elos Expertline supplements water changes may be reduced in frequency to as little as 1 time every 3 months or less. Use extreme caution when attempting major changes in a short time this is best left for experts.