It is worthwhile itself in any case, products it nearly daily needs (fodder, filter sponges, water treatment, etc.) to always along-order.
Forwarding expenses become higher thereby in no case. Completely on the contrary, if it over the 80, - euro border come, the shipping flat rate becomes even more favorable, and/or is omitted completely.
The more products you order the more favorably become it then, because the shipping flat rate divides itself on several products and in such a way saves you indirectly again.