Whoa canndo thats awesome Im gonna have to follow in your footsteps
Set up a code with your spotter, never be in the tank under the influence of anything without someone - someone responsible - outside of the tank. Set up a system to have your spotter realign his attention to you and your situation every half hour, a flashing light, a bell, something to catch his attention as he will be bored and if he reads (what I did most) he will lose sight of what he is there for and forget about you.
Rig a way to pipe sound into your tank if you can and arrange with your spotter the types of music you would like to hear and when, it should be turned on or off. (we tried simply pumping sound into the tank and it does not work, you need earphones - the echo otherwise will drive you nuts in short order as you will be concentrating all of your attention first to the music and then back in to yourself - that is if you want music. Silence is great - word loops are very interesting and will take you to some extraordinary places - even if you don't use any chemicals at all. I once tried books on tape while on a low dose of acid - I will leave that to your imagination. NOT taking anything and being in a tank takes longer to hook in but once you do, everything is moved within yourself.
You can experiment with witch's chairs, or even soft white hemispheres over your eyes and noise canceling headphones if you cannot get to a tank.
I found the k to be the most disorienting and least "secure". Interestingly some of the other chemicals are far more calm and directable.
If you are interested, pick up some books by John C. Lilly, especially "center of the cyclone" about his experiences with LSD in tanks - there is another one but I can't seem to recall it.