Algae and PH issues

Looking for some thoughts on these issues. My tank's PH is running consistently high now for two months at about 8.5 to 8.6. It goes down to 8.3 something at night. I do weekly 25% water changes with Instant Ocean Reef crystals which I've used since day 1. I use RODI for top off.



Salinity shows 1.023.



I also have a problem with red slime algae which I can't get rid of. Tried anti-biotics months ago which worked but then the tank cycled again so I'm doing that again. I tried red slime remover with no results. It's been about a month now and I clean the green algae off the glass daily, blow out the rocks and siphon the sand about twice a week and change the filter socks usually twice a week. Doesn't seem to help at all. This is getting quite frustrating. I don't have any corals yet so I turned the lights off for 3 or 4 days and it keeps the algae at a minimum. But, as soon as I turn the lights on, within an hour, I've got red spots starting and within two hours, it's all over again.



I've tested for nitrates and everything and it all shows 0 on the readings. I've added PhosBan to the sump and that hasn't helped.



Just changed my RODI filters last month.



I have two Hydor Koralia 1150 powerheads pointing at each other from each side of the tank. I'm being told by some people to get two Evotech Vortech pumps. Not sure if $800 is going to help the problem though. I have a 1200 gph main pump- Danner Super mag 12. I'm thinking the flow is good.



Any suggestions? Thought? Tricks?





Tank- 125g Perfecto 6' long reef ready

Skimmer- Octopus Diablo xs160-

Return Pump- Mag 12

Powerheads- 2 Hydor Koralia 1150's. (

Heater- 300w Eheim

Lights- Two Apollo Reef LED Solarblast UV 5000+ dimmables-

Sump- 40g Aqueon- self made sump-

Filter Socks- Eshopps dual filter sock

Controller- Apex Neptune

ATO- Spectrapure

RODI- Spectrapure Maxcap-90

Rock- BRS Pukani and Reef Saver rock combination - 80 lbs total.

Sand- Figi Pink Arag