1. Go get a cheap OTO/phenol red test kit at Walmart or somewhere, and test your water. Report the results. BUT . . . continue adding chlorine sufficient to maintain a DARK yellow result the following AM. However, add the 3 gallons at least one more time, AFTER brushing the pool 100%. You want to make sure you've stirred up, and exposed all the algae to chlorine.

2. Go ahead with your plan to get a K2006; you'll need it.

3. BUT . . . you'll also need to order replacement cartridges. The Intex cartridge work fairly well . . . if you follow the manufacturer's guidelines and REPLACE them every week or so. They are not high-quality enough to clean successfully. The "Super Simple" recipe for soft-side pools (link in my signature) has links to Amazon Unicel and Filbur cartridges that will fit.

4. It's going to be a while before you have the K2006 and the cartridges. If you have used a floc successfully in the past, and can settle most of the algae, and vacuum it out . . . DO SO. You can use the high quality cartridges to remove what you can't vacuum. But do not try to floc it, till you are SURE it's all dead.