First of all, you can use a kalk paste mix in place of aiptasiax.
Here is how you decide which way to go.
If the aiptasias are isolated and easily reachable by your syringe, use aiptasiax.
realistically, not all aiptasias are isolated, they can grow in the middle of a zoa colony for instance, you most certainly do not want to blast aptasiax into the aiptasia since you will get some major collateral damage, unless you do not care for the zoas.
In this case, you can use peppermint shrimp. for best result, take the rock or whatever the aiptasia is growning on out into a QT tank. Put your peppermint shrimp in the QT tank. It may take a while, like a week before the peppermint shrimp finds the aiptasia, but once it finds it, it will eat it clean without any collateral damage.
The least desirable of all cases is if the aiptasia is not easily reachable, and taking the rock out is not possible. In this case, if you add the peppermint shrimp in your DT, it may never find and eat the aiptasia because there are other food sources more readily available. This is where the hit and miss part comes in using peppermint shrimp.
they don't call aiptasias pests for nothing.
good luck.