Help with dwc question please

Ok,
So I started dwc with 5 gallon buckets, had to go on vacation and switched my buckets to a 35 gallon rubber maid he he. So long story short I use the lucas method but the newer version where you just top off the water instead of doing complete res changes and keep the ppt @ 1300 @7 conversion. So I use ro water and the ph has been great and everything has been decent except for a little budrot (high humidity).

So now I am into my third grow with the same water, and I am finding that my ppt is staying constant @ 1100, ph is constant at about 5.5, but the thing is iI have not added nutes to my addback water except about once in the last 3-4 weeks.

I have examined the ask lucas thread and I know he says that he has run 3 flower cycles with the same rez, the issue he says he finds is fluctuating ph after 3 runs.

So, it seems as if my ppt is not going down anymore even when i add more ro water it barley budges. Either my new set that has been in there (purple power and nlxbb) does not eat almost any nutes or something is goign wrong.
Other problems I have (i know I am working on them) rez temp fluctuates from 72 to 78 right now, (damn it's hot) and room temps are at 85 at the highest...
any suggestions or experencies besides what I am probably going to do wich is drain the rez and start all over with new water ( this I don't want to do it is a pain)?
Thanks in advance I know this is a long winded read.

Ok my plants were bigger, greener, better tasting, and stress free when I used this method.
Fresh res.
Top off once or twice weekly with plain water. For nute hungry strains top with 1/4 dilution of your normal dose. this means if your starting ratio is 1ml/gal to mix the res, your add back water should be 1/4 of that. for others i add plain water or water with addatives(sweet, superthrive, cal-mag, liquid karma, whatever u like). Learn the language of the plants to see what they are wanting.
When you have topped the res with the same amount of water as used to mix a fresh res, start with a new batch of nute soup. So, if you started with 5 gallons, top, and top, when you have added 5 gallons, its time to make a new res.
This works great for me, and ive got the timing down now where theres no need to flush my plants. Bubblers need only a very VERY small amount of nutes to flourish. By the time I am nearing harvest, the plants have already drank one full res of water, and by harvest the nute levels are very low. I change the water in my bubblers once/month. Thats all thats needed to maintain my garden. NOTE: the numbers will change with variables, such as lighting, res size, strain, etc. But its all the same logic. The key to a succesfull crop is keeping everything as constant as possible.

appreciate the advice, this sounds similar to the lucas formula with the addbacks, I think this next go round, or even starting with what I have going I will try that, once I hit about 30 gallons in addback water I will then empty my rez and start fresh again and see how that goes. The more I examine it, it seems like I must be having some type of lockout problem, probably because I have not completley changed my water for about 5-6 months.
Also I did not mention, how I was doing. The first 2 grows of a white strain came out well, nice buds although in the biggest cola on the 1st plant I had budrot in the middle, I am thinking this was humidity driven, 2nd set of plants looked good nice buds again in the 3 largest colas I had some small budrot, although I was looking for it this time so as soon as I chopped those they got clipped into much smaller pieces to dry faster. Now I am in my 3rd grow 2 diff strains same water and the buds look ok not great, but one of my plants is def showing signs of deficency the other seems to be doing well so far but I as always am worried. I will completely flush and start over and see what happens, and then report back.
Thanks for the input kush

What i did forget to mention is that, even though I am doing the "lucas" formula, when Its time for a res change, I always flush my plants with clean water, h2o2, or clearex for one day before I make a new soup. Play around with these scenerios for a little while an you will find the method that suits you best. But I would not go for longer than half of a normal flower cycle without changing water. My plants get one water change in there fruiting cycle. Also, depending on your nutrients, there may be no need to use a ph adjustment, and If I were you I would experiment with using half of your normal nute load and NO PH ADJUSTMENT (vets are gonna jump all over this). If the plants look fine, stick with it, if they show signs of defeciencies, increase the load in minimal quantites untill the plants find a level they like. A ph problem will present itself as a nutrient defenciency also! remeber that most hydro nutes are Ph adjusted already.