Assassins not assassinating

[Zoeeannee]

I have a 300L freshwater which is inundated with trumpet snails. I have done some quick maths and the bottom of my tank is about 5000 sq CM. In any one 25 sq CM patch I can see (this obviously doesn’t account for those under the sand) about 25 snails average. So that means about 5000 trumpet snails - insane I know!!!
I have 5 assassins and I appreciate they have a tough battle on their hands with a 1:1000 ratio but I have had them for 2 weeks now and if anything the trumpets are getting worse.
I know that trumpets get worse with over feeding however I have corys, along with slow and fast moving fish so difficult to make sure everyone is fed, although I do not excessively over feed maybe 5-10% over some of the time.
Do I just not have enough assassins? Having worked out the numbers for the first time today I think this might be the case, however maybe they just take a while?
Can anyone advise on this please? Thanks

 

[Circus]

With this amount, the trumpet snails will breed faster than the assassin snails can eat them, although the assassin snail will (eventually) breed as well. I would take a net and sift through your sand to manually remove as many trumpet snails as you can. Snail traps are also an option for manual removal. Once you get the trumpets down to a reasonable level, the assassin snails will be able to slowly keep them in check. I doubt you will be able to eradicate them entirely without a complete tank breakdown.

 

[Car1os]

What you ask of these snails is kind of impossible. Just go through the sand and get out as many as you can.

 

[PheonixKingZ]

With this amount, the trumpet snails will breed faster than the assassin snails can eat them, although the assassin snail will (eventually) breed as well. I would take a net and sift through your sand to manually remove as many trumpet snails as you can. Snail traps are also an option for manual removal. Once you get the trumpets down to a reasonable level, the assassin snails will be able to slowly keep them in check. I doubt you will be able to eradicate them entirely without a complete tank breakdown.

I concur - there is no possible way for the assassin snails to keep up with the ever-breeding MTS.