Hi, my first post. We have had a flow hive for about 5 years and it’s been good. Last winter it may have swarmed - the bee numbers dropped a lot, but it’s built up very well again. In the past it’s had a few ants but not a great worry. However the ants have now built up badly and we have masses of eggs and ants all through the super. They’ve even eaten out some of the timber edges of the flat super roof panel. The honey we harvested yesterday was contaminated with a lot of ants and eggs and debris. I suspect the presence of the ants slowed down the honey flow, and reduced the total volume. We filtered it very successfully however, and it’s great honey. We want to control the ants however. I’ve seen a lot of articles about methods to prevent ants getting up into the hive … the flow hive accessory barriers, water trays, grease or vaseline etc. But I wanted to ask … if the ant colony is well established, will it die out soon if we effectively block the ants’ access to and from the ground? Or will the colony be self sustaining in the hive? Perhaps we need to remove all the flow frames and clean them thoroughly as well blocking access?? (the ants seem to be inside the flow frames too). Sorry for naive questions!
Hi and welcome to the forum! No question is too naive when you’re learning 
It sounds to me like you should thoroughly clean the hive equipment to remove ants and eggs, as well as treat the surrounding ground. I would also consider rehousing your colony into new equipment, so you can scrub and sun-dry the gear to remove any pheromone trails that will attract more of them.
I think you got good advice above from @Eva .
I would also make sure whether you have any foliage (touching or close)or over hanging branches…even if itlooks clear, the wind can blow a tall weed or branch over head where something can drop onto the hive. Maybe do a sweep of the area for any launch points.
An extra preventative measure you might like to take. Dependent upon your setup of course.
I had an ant problem and I placed small oil moats around the feet of the table stand. The issue stopped straight away.
I’ve a similar problem - I had effective ant moats but one was empty for a while when we were away and small ants have established somewhere (3 hives Langstroth hives on one stand). I’m keen to hear how your clean up went as I’m not really sure how to start. Cleaning and/or replacing the boxes seems relatively straightforward - but what about the frames - or is this not where they make their homes? Anything safe I can put on the wooden hive stand that will help get them out of nooks and crannies? Any tips appreciated.