How to remove ammonia in a closed pond?

Dear fish growers.
I have a question.

I live in Latvia which is hot in summers (+30 ℃) and cold in winters (-20 ℃).
I want to raise rainbow trout in my backyard in a very small pond. Trout does not love any heat and therefore the pond will be in the ground and will not be exposed to direct sunlight. It will be aerated and the water flow will be ensured throughout the year as is required for trout. At the same time the pond will be isolated with membrane from the soil.

The problem I have is this:
How do I get rid of the ammonia in the water during summer and during winter?

For summer I have an idea to have a hydroponics setup therefore making the whole system as aquaponics which will clean the water for fish from toxic ammonia by converting it into nitrate, a plant fertilizer. But maybe there is a better way for that in summer?

And I have absolutely no idea how to remove ammonia during the cold winter.

Thanks for your help!

Andris,

I recommend reducing winter feed. Biological activity in winter temps is subdued and so may not be able to keep up with rates of feed.

You can control ammonia either by reducing feed rates or by increasing the C/N ratio of feed inputs. Fish need higher % protein feeds than allows for that however. So usually the Carbon is increased by separately adding sugars or starches to the water. This provides the additional energy required for yeasts, bacteria, and fungi to metabolize the ammonia. In a TP culture, this is food for the fish (even flocs are harvested and incorporated in feeds to result in zero emission aquaculture with no water change). But in trout culture ... probably not much help. If you want to know more about it google Biofloc Technology and see where this takes you.

Probably the best approach with Trout, a fish with more stringent water quality requirements, is to feed no more than can be handled with available water exchange capabilities. This might also require reducing the number and weight of trout one is trying to produce. Try to understand what your limits are and design within them.