Help! I cant get rid of this brown algae!!

How about the water?

That immediately made me think of dinoflagellates. 

Well I am just recovering from the same slime. I can see in your pics that you have a mix of stuff. I did adjusted the lighting frequency down to the 460nm side 20-30 degrees. It did help some, as the algae eats up the light. My big prob was my R/O water filter need the filter changed and it took me some time to clue in. Chlorine bad. Yes, all my test readings were zero but one, ammonia and only after dosing prime did I see it pop up. This is how I know I had a chlorine prob and I changed the r/o filters. The ammonia test don't read chlorine but the prime turns the chlorine in to ammonia lucky for me I was able to figured this out before I did to many water changes.

I have ran MH 5-6 hours in a day and did very well so you could cut back and it may help. I have also read that in a turf scrubber the brown slime algae is gotten rid of by reducing the time to less then 8 hours.

I would think the DI would go before anything else. I have changed mine a couple times already and haven't touched the other filters.

I did not change the r/o membrane I changed the carbon and chlorine filters. Now I test the chlorine as well as keep an eye on the TDS meter.

I think if you kill the lights and stop adding food that will die of in a few days.  then resume with less lighting and feeding.

It doesn't look like the dino I have. If it is, you would see it grow upwards and it looks like slimy strings of snot, literally. Had air bubbles in some places. Yours reminds me of the cyano that is in my lfs that is taking over their tanks. Does it blow off the rock? Dino will not and it gets worse after the lights have been on. Try to suction out all you can with a small hose. And keep your lights off for a couple days. Do you run carbon? If you do try chemipure elite. However, since you are gonna upgrade, you can also take the rock that has it growing on it out and put it into a rubbermade container scrub it, and store it in saltwater in complete darkness for a week or so.. Now, as far as membranes go, you are supposed to change the membrane after so many gallons, I change mine yearly. My ro/di 6months to a year. The carbon and sediment cartridges get changed every 3 months regardless of what my tds meter says. Hope this helps.

Cyano is a bacteria. Hard to kill anymore imo. If the things you are doing do not work, the other option is to use chemiclean. A red slime remover. You must follow the directions though. I have heard recent talk about some cyano developing a resistance to it, so it may not work. If it does work, it does a very good job. I would change your ro/di filters and membrane too. just my .02

Ever maintained your sandbed?

old sandbeds don't just need a few more nassarious snails and cucumbers to turn over the sand. Occasionally... every three to five years... you need to go through your sandbed with a VERY small gravel vac with a really low flow/suction and get out all of the built up detritus, nitrate and phosphate in the sand. You'll pull out some foul smelling black/brown mess. If you don't maintain  your sandbed every now and then, you'll never get a hold on your nitrate/phosphate/detritus/cyano/algae problems once it settles in. It's just one of those old tank syndrome things...

 

There are also other factors... nitrate and phosphate present in the water column, old bulbs, too much lighting, not enough flow, too much detritus build up in the live rock, clogged up live rock etc. etc. etc. Sometimes water changes and macroalgaes and more flow and less lighting isn't enough, especially in older tanks with sandbeds that aren't maintained.

 

Not to be rude or a jerk......But IMPOSSIBLE NUMBERS!!!!!!!!!!  Look at things theoretically you will not have 0's across the board.....Given the shear nature of life and how things work, there is always some bi product or waste, and your numbers are telling me I'm crazy......What test kits are you using.......

Wow......Where did you buy your filters from......How big is your RO/DI unit....You can buy a 6 stage filter replacement from BulkReefSupply for roughly $48.00.....A new membrane Dow FilmTech for another $40-50.......

 

Snake also hit on something I thought as well.....When he mentioned about Phosphates.....That Phos binds to your LR......you might be or assuming your removing that source of Phos, but your rock could steadily be leaching, and will continue if that is the case and point here.  That is were the Bleach / Acid bath helps in this type of condition.  Again not saying that's what it is, but a very good point by Seth.......

 

 

Seriously. My membrane is 109.00, my di is 40.00, the carbon is 4.99, and sediment is 7.99. I usually buy the three pack of the last two to save some money....