Andy,
the Pool Store method of pool keeping and the TFP pool keeping method we subscribe to here are vastly different. To be honest, we simply do not trust pool store testing, and trust 1000 times less, the advice they give.
Remember one thing. The pool store is in business to sell you stuff, and lots of it. Do you need it? Well they are going to say yes because they want to sell you stuff. They NEED to sell stuff to stay in business. Remember that.
OK. Regarding your filter, backwash it and make sure its as clean as it can be. Record the reading on the pressure gauge.
When the pressure increases 25 percent, then you need to backwash again. It isnt a matter of every 24 hours to 2 days or 2 weeks. The pressure gauge is your indicator that it needs backwashed.
Now for the rest of the story - The TFPmethod which is followed by everyone on this forum is about putting only what you need in the pool water. No one here will try and sell you anything. You may however get some recommendations of what to buy, which is part of the education of learning how to manage your pool.
The TFP method requires you to have a good test kit. Only a couple are recommended, and you can order one here.
www.tftestkits.net
For what its worth, almost everyone here recommends the TF 100 because it contains more quantity of the testing chemicals so you dont have to replenish them as often. The Taylor K 2006 is also excellent, but you will have to order the testing supplies more often due the low quantity.
You mention you have some algae. Getting rid of algae will require a lot of testing, so get the XL option if you choose the TF 100 to make sure you have enough test supplies to comeplte the process. The Taylor will not have enough and Taylor does offer an XL option. You will also need a lot of patience, because getting rid of algae is not a one time pop. It is a process that takes time. Once the algae is eliminated, then following the TFP method is simple and easy and will have to worry no more about algae or be at the mercy of the pool store, which I promise you, does not have your best interest at heart.
Recommend also at the top of this web page, you click on the Pool School button and read read read...
Once you have your test kit, if you post the test results here, there are tons of people who can help, give advice, and teach you how to keep a troubefree pool which will be much lighter on your wallet, and your nerves, than any pool store could ever do.