Crowfoot shopping area is at Crowchild Trail and Nose Hill Drive nw.

That's a good idea. I wanted a smaller micron sock than what I could get at wai's. And as for set backs... If the tank looked the way it did a year ago, I'd be way more cautious about this. But when you've not got much else to lose, it's less scary to experiment.

90 degree elbows. Got to get a pipe from my rerun line back to my filter sock area

Dangnabit. I basically drove right past there on my way to Home Depot.

So, you're advocating using roughly 50mls of GFO in my 105 system, instead of the BRS recommended 225mls ? ( For my tank they recommend 0.86 cups )

Your ammount equates to;
105/30=3.5 Tbsp
3.5x15mls(Tbsp)=52.5mls

I get all the hype about selling product and such, and some may not change their media when they should, but that's a big difference

I'm asking as I'm considering your recommendation for 3 reasons;
1 - I have GHA that I suspect is living off the iron from the GFO
2 - My corals have become 'too green' after the last GFO I bought
3 - I'm looking to cut costs

I'm also considering cutting GFO out of my tank's diet altogether as it's getting old enough now

Gfo is like any other product, the amount you "need" to keep phosphate levels at a certain set point won't ever be determined by tank volume.
It will be determined by the rate of addition of phosphate. You could have 10000 gallon tank with three fish and brand new ceramic rock, and you'll probably need less gfo to keep phosphate at "reef" levels than a 300 gallon tank with 40 fish and 7 year old rock. Whether "less" means smaller volumes changed more often, or huge quantities changed every 3 months, the amount you need is dependent on the amount you use. Just like carbonate or calcium.

Gfo can certainly reduce phosphate levels. My... Question (I guess?) is whether gfo can reduce phosphate levels to the point where the extra iron, in some cases, doesn't negate that benefit.

Foz Down alone can remove phosphates to the point(150ppbillion) where it is not reliably tested by most electronic meters, meaning the meter's margin of error is greater than the phosphate level. With Foz Down there is no need to use GFO and suffer with the other issues that GFO and reactors bring along.

Wai's should have 10 micron 4" diameter filter socks.

He didn't seem to, but none of the socks I saw there listed the micron size. He didn't think any were smaller than 100 micron.

They are the 10 micron socks at Wai's.
They're the same ones I got from Tim.

I got the smaller micron socks. Had to put it inside a larger square sock as my square holders are just the tiniest too big for them.

Next step that's frustrating me is this freaking Hanna LR phosphate test kit. It's been months since I bothered testing for phosphate because of this issue. Test 1: 33 ppb P (about 0.1 ppm po4). After a water change a 1ml dose of phozdown (probably to small to do much in my size tank), test again. 44ppb P.

Do a dummy test with pure distiller water... 22ppb.

Glass vials are notorious for adsorbing small amounts of phosphate. In high end labs, they wash the glassware they use to run phosphate tests in hydrochloric acid regularly to remove it. The last time I was regular testing P, my "level" was predicted by how many tests I'd done, not what was actually in the tank.

Anyway I just acid washed and and dummy tested my vials again and I'm down to 16ppb with distiller water, which might be the actual amount in the water jug I bought from Safeway, but it still makes it hard to trust the test.