First thing, get rid of the strips and get a decent test kit. I would recommend investing in a Taylor K-2006. It will be money well spent in the long run.
As far as the Pool Stain Treat, it is actually a reducing agent. I chemically transforms the insoluble colored metal stains into colorless and soluble metal ions that go into solution.
The metal is still in your pool and can redeposit as stains if your water chemistry gets a bit out of line or your water can become colored if you shock the pool.
Adding a metal sequestrant such as the metal out makes the metal ions in solution non reactive chemically so they are much less likely to deposit back as stain or color the water. However, sequestrants do break down and need to be reapplied on a regular (usually monthly) basis. If not your stains are very likely to return.


So to deal with metal stains you need two products:

1) a reducing agent such as ascorbic, citric , or oxalic acid to reduce the metal to a colorless, soluble form (Ascorbic is the least toxic, oxalic is the most toxic but relatively cheap.)

2) a sequestrant to keep the metal in solution and inactivated chemically so it does not react with pool chemicals to deposit as stain, precipitate out (rusty water) or oxidize into a colored form (green water for copper, yellow water for iron, purple water for manganese). Most of the sequestrantss on the market are based on HEDP (phophonates or phosphonic acid derivatives) and are the most effective. There are also ones based on EDTA that do not raise phosphate levels (really a non issue anyway!) but they don't work as well as the first type. However there are other chemicals used as sequestrants and chelating agents in pools so YMMV. (Also all chelating agents are sequestrants but not all sequestrants are chelating agents. The difference lies in the shape of the molecule and nothing more.)

Also, stain removal is more effective at lower pH so you might need acid and since most stain removers destroy chlorine (and you cannnot shock because that will bring the stains back) you will most likely need some polyquat 60 to keep algae at bay until the chlorine is holding again.

Don't forget that calcium is also a metal so sequestrants are also useful when there is very high calcium levels in the water.

Hope this info is useful.