1.5 Year 80g update, experience, and looking for advice

[Hiachi20]

Hello everyone! I've had my tank for about 1 and a half years now. I'm going to list off some things I think are cool or learned or am looking for advice for.

Info
It is an 80 gal with about 20 gal of water in the sump. Durso standpipe for overflow and a reverse Durso on the other end with a 700 gph return. I usually use a sock but I'm considering not at all. My nitrate tested at 15. Phosphate at .5 or 1 or something. I use vodka occasionally. I try to keep the oxygen up but the pH doesn't come up much so I put in some alkalin8.3p. The lights are in two pairs: white and blue, violet and red. Truelumen/wavepoint. 48 inch t5s. Lights are violet and red are on at 0800 to 2230 and white and blue from 1100 to 1900 with blue moon lights from 0600 to 2300. The sump has a basic cheao led bulb and 3 current USA 1 foot led lights. Blue, blue/white, white. Bubble magus curve 5 skimmer with a new pump. Chaeto and caulerpa in the sump. I test salinity, phosphate, and pH. Constant 700 gph powerhead and sometimes 3000 gph for debris flow and exercise. The temperature is usually 77-80F from equipment and ac alone. Always.

Questions
Suggestjoms are lighting times?
My return tube is kinda black or dark where the lights hit. Should I replace it?
What things should I mostly test for next? Alk?
How can I get the mushroom or anemone to reproduce? The Condy doesn't split and the mudroom is in a spot where it's not coming out.
How are the lights and parameters for my macroalgae growth? I just got it so idk yet.
Should I get rid of the urchin for the sake of coralline or hope the coralline out paces it now that the tank is healthy.
What suggestions would you have for my tank setup and techniques?
Would the 3000 powerhead in the return area be beneficial in any real way? Adds some flow and heat.
Should I buy a heater? Could I get away with a tiny one for the extra couple degrees? Heaters scare me.
What live things can I put in the refugium for overall benefit?

Some things I've learned
First of all, stability is key. The cowfish having ich or fungus was easily solved by using copper power. 3/4 to full dose is usually effective. No adverse effects of the copper seemingly. The hydrometer is not accurate but you can guess decently precisely if compared a couple times. Mix saltwater by adding salt to the water not water to salt. Mix it for a longer time than just a few minutes. Flow is key with the quality of mixed water. Chemicals are terrible to use period. Polyp lab medic doesn't do a dollars worth of work to ich. Your fish will die.

Getting a picture of the cow fish's tail fin open is a rare thing. But it is pretty

 

[ZoWhat]

I counted 13 questions.....