+ A test result of 6.8 means 6.8 OR below, not 6.8 exactly -- add borax, 2 boxes at time, till you get your pH above 6.8. It doesn't have to be much above, but pH below 6.5 can damage your liner.
+ Most likely, you have algal sludge on the pool bottom. You'll need to vacuum this to waste; you can't really remove it with a DE filter as it will plug the filter almost instantly. With a DE filter, it may be necessary to change the piping to make this possible.
+ Circulate your pool on bypass, not filter. If necessary, remove the filter internals so you don't plug them with algae, and don't have a valve that allows bypass ("recirculate") flow.
+ If you have sludge, adding chlorine and algicides may well be a waste, till the sludge is gone. That kind of gook can consume enormous amounts of chlorine, and then come back for more.
+ Once the sludge is gone, you can start work on the chemistry. Till then, just worry about the pH.
+ When you get your kit, test pH, TA, & CH only. Don't bother with chlorine or CYA -- there is none, and the kit only has enough CYA reagent for 4 tests. That's can be enough, if you only use it when you need it.
+ Plan on it taking a couple of weeks to clean up the pool. It might not take that long, but don't get your hopes up.
+ If you are in a real hurry, vacuum to waste till the pool is down to the lowest safe level -- with a vinyl pool this means 1' above the HIGHEST liner covered horizontal surface. Then start refilling AND adding bleach at the same time.
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