1 plant, 1 question, 1 problem. <Budget Grow>

My tips are curling down but my area is always 72 degrees at night and 78 MAX on its on-light cycle and the light is an HPS 150w about 12" from the plant so I know its not a heat prob. Im sure im an idiot for not naving a ph tester but Im disabled (hence the legal right to grow medical mj) this is my first plant and I didnt have the money so im kinda buying stuff one piece at a time pretty much. Last night, when I took these pictures the tips werent as curled down as much as they are now when I went to turn the light on at noon today. They are curling down on several of the tips and they look almost dry and cracked. I did mist them last night with H2o, waited about an hour till they were dry and then misted them with Safer brand insecticide soap because I had been noticing a few gnats in the closet with it. I wouldve rather not done both sprays in the same night but it had been about 4 days since ive misted. It may have messed it up doing the H2o first since it opens the leaves "pores" and couldve let the spray INTO the plant Im supposed to be waiting 5-7 days before spraying it with Safer but I only waited 4 days because it should start to flower soon and I definitely dont want that crap in the buds, even though its "Safer" organic spray. Please dont tell me to check the Ph because like I stated, I have no job and a family that I have to spend my little bit off money on. If you honestly think that it is actually a Ph prob just please tell me how to straighten it out. About 4 days ago the leaves were curled to the sides, then they looked good for a few days and now they are doing this (curling down).

I do have another question. I have heard about people "flushing" the plants before flowering begins. Can somebody please tell me what this is and how to do it, and why its done.
Ill post my specs and pics on here for you guys to see.
***I am keeping a daily journal for the plant so if you need daily info to help me fix this just ask.***

*150w HPS (for its full grow)
*Its grown in clay type dirt because at the time of getting the plant I didnt even know they made special soil
*Avg. temp 75 degrees
*Avg. Humidity 50%
*Its circulating in the closet with a small shelf fan but the closet door is always cracked so it does get the bad air out and good air in
<I know im missing info but like I said, I have a daily record so just ask>
*

A pH tester is the only tool a grower really needs imo. The only ways someone can get by growing without one (without the plants showing problems) is by using a specific soil/nutrient mix where another grower already worked out the correct pH as part of the recipe, by watching the plants and adjusting the soil pH over time based on plant symptoms, or by getting lucky. Neither lasts forever, though, and growing long enough without checking the pH will eventually cause problems.

That said, pH isn't the only concern. The soil doesn't look as good as maybe it could be. What are you growing it in?

If your medium has high clay content, you may not be draining properly.....

@Mother --- OK Ill see what I can do as far as getting one. How much are they or at least what can I search for online to find one? (I dont wanna end up with a bunch of pool supplies popping up in my search)
Like I said they soil has a lot of clay in it its not nice bagged soil. I didnt even think to get one because when I got the clone it was only about 6" tall so I put it in a normal sized pot and it started growing really fast so i took some plain ground garden soil that I have had really good luck with growing veggies in. Its the same soil that I cross bred a strawberry plant and a cayan pepper plant last season in. Im actually REALLY good when it comes to gardening but this is a whole new ball game, Sooo many problems and concerns.

@OldReefer ---- I have already thought of that and drilled some holes in the bottom of the bucket so that at least the h2 can get out. I actually had some really droopy leaves a while back and that seemed to fix that.
Do either of you know about "flushing" the plants?