Well, i knew my pH was comparitively low, but after installing and calibrating, and recalibrating a pH probe (Reef Keeper) it seems damn near impossible for me to raise my pH. I've been trying to use Reef Buffer (Seachem) but it only raises it to 8.3 for a couple of hours and then it goes back down to my current pH of 7.67-7.8. I then did daily doses of this stuff which consequently caused a slight tank crash and now my return pump is acting wonky and the water level in the return pumps chamber has decreased substantially.

Needless to say i'm pretty confused as a) I've used way more of this reefbuffer than the recommended dosage and still the pH refuses to budge and why would that affect my return pump?

Any thoughts are much appreciated

Dunno about the return pump unless you have built up a layer of Ca precipitate scale in the impeller chamber.

Have you checked to see if you have elevated CO2 levels in your house?

1) Collect a cup of tank water and record pH.
2) Aerate water for 1-2 hours, re-record pH.
3) Take cup and air pump outside, aerate for another 1-2 hours and record the pH.

If the pH doesn't change or goes down when you aerate it indoors but goes up when you aerate it outdoors, you have elevated CO2 in your house which is depressing your pH.

what is your alkalinity?

Being overly concerned with PH is what everyone seems to do, but as long as your in range, its ok. ALK is the factor you need to make sure stays around 9dkh. If your alk is good, then ph from 7.8-8;4 is fine.

Buffers for PH are not good to be messing with either. Id stop using it.

Also, how are your tank inhabitants? If things are doing well this whole chasing the perfect PH is even more useless

Test your alk! I had the same thing, 7.51pH by nite, and around 7.8 by day!! My alk turned out to be around 4.3 dKH I discovered!! I dosed in alk for a few months and my pH finally started hitting 8.19 by day and 7.8 by nite. Also in the beginning I'd notice that when I dosed, pH would spike for an hour and then drop back down... But over the course of a few months, you will notice the differance.

I was having all kinds of fluctuations with mine too till I went to adding kalkwasser to my top off water and now I have not had to add any buffers or calcium. Calcium has stayed around 400 and alk at around 10dkh and ph during the day is average 8.4 and early morning 8.1.
Diatoms and cyano has pretty much gone away also.
and I am finally starting to get some coraline growing on the rock.