Yeppers you sure do.
I would worry about the essentials first. Ca, Mg, and Alk. How large of a tank do you have? How often...and be honest (lol) are you doing water changes and how much? What are the corals that you house in your system? What salt are you using?
Once we get your very important elements up we can start working on the PO4. You will see a reduction in PO4 with some water changes also.
Getting your alk and ca up should raise you pH to normal levels. If you have a small tank, a basic two part dosing regimen should work well. I use Seachem Reef Complete for calcium and Seachem Reef Builder for alkalinity since that is what the local stores offer, but any 2 part should work well.
What salt are you using? When I was using Instant Ocean I had to dose a lot more than I do now that I'm using Reef Crystals.
i use reef crystals salt. tank is a 55 gal. i change 8 gallons of water per week. i use a typhoon III ro/di for my water. corals include shrooms, rics, hammer, frogspawn, starpolyps, zoas, xenia, claustrea, various sps frags. my sg is at 1.025 and temp is 79.8.
You might want to mix up a new batch of water and check the Ca. Reef Crystals had a bad batch earlier this year and the Ca and Mag was way low.
I kept dosing and dosing and couldn't get the Ca and Mag up. Took me a couple of months to figure out it was Reef Crystals. Since then, I've heard of several more people with the same problem.