Light mold in the attic

I was digging around through my attic and noticed it wasn't properly ventilated, and on top of that I only had R19 fiberglass bat. I had 5 quotes to re-insulate with cellulose and fix the venting. Out of the 5, 4 said there was "moisture and discoloration" and the last guy said "No, you have some mold". Based on testing I have done with a test kit from Home Depot, all of the spots the one guy said had mold, has mold. I tested multiple trusses through the attic and some have some growth while others don't. All the other guys wanted to sprits a little bleach mixture on the problem areas, fix the venting and insulation, and call it a day. This last guy wanted to sell me on an $800 mold removal using sanitizers then spraying down the wood in the attic with an antimicrobial mixture. He also is a certified mold removal professional, so there is a conflict of interest.

I had to look pretty hard to find some mold spots on wood throughout the attic. Nothing is growing very visibly. But no way in hell "spritsing mold areas" would get all of it.

My question is, Who should I believe? Would it be wise to have the attic sprayed down?

$800 does not sound unreasonable unless you want to do the work yourself.

When we bought our current home there was a little bit of suspected mold in the attic from where the bathroom vent fan wasn't properly vented. The home inspector suggested spraying with a bit of bleach/water mix would resolve the issue. So I wouldn't discount that method too quickly.

Spraying it with boric acid will kill it, and stop it from coming back.
Do a Google search on Boric Acid. One brand name it's sold under is Roach Away because it also will kill millipedes, centipieds, roaches, boring bees, powder post bettles.
Lowes, Home Depot, even Wall Matrt sells Roach Away in the pesticide area.
Bleach will do nothing to stop it from coming back.

Here's what I decided to do.

I did a thorough inspection of my attic. Looking between every truss. Examining my current venting, and taking a few samples of what I thought to be mold. EVERY sample grew within 48 hours. I then proceeded to read up on mold growth, mold life, etc... Turns out, mold doesn't die, it goes dormant. The oldest mold I read about was found in a rock that was 25 million years old AND IT WAS STILL ALIVE. Out of the 5 quotes I got, only one guy said I should take care of the mold. Everyone else said "it was moisture" or "they'd spray spots down with bleach" or "You know what causes mold growth? Moisture. Take away the moisture, you take away the mold growth". If any one of them were right, it was the last guy. Yes you can take away the moisture, the mold will go dormant, and you will have no more growth, but it won't die. My biggest concern with that approach is the staining left behind from the mold. If I ever went to sell the house, an inspector would immediately flag it for previous mold and make my life a living hell to prove it wasn't growing.

I'm all about doing it yourself, but between the size of my attic, the heat, and the life of mold... I have an appointment this Friday to have it sprayed down, fogged, and antimicrobial shield applied, new 24" baffles installed, new soffit vents cut in, a power attic fan cut in, and they were only about 900 hundred more than my cost to rent a machine from home depot and blow in R60 worth of green fiber, so they are doing that as well.

This is one project I don't mind sitting out and paying the pro's. They will do the job right, and give me a written lifetime guarantee concerning the mold. This particular company has been doing this since 84', I hope I made the right choice and my experience goes well.

Good for you!! do it once do it right.

Here's one more thing for you to look into.

The moisture in your attic might be due to humid air from the conditioned area and your basement (or crawl space), leaking into the attic due to the "stack effect".

Since you are going through all this expense to optimize the attic, I suggest you also air seal it, isolating it from the living area. Have a home energy auditor perform a blower door test to detect leakages and thoroughly air seal the home.

Also check the ducts for leakage, specially if they run through the attic.

Insulation and air sealing qualify for federal tax credits - check the US Department of Energy site for information - which will help you pay for some of the costs.

Proper air sealing and attic insulation will also save you a lot of money in cooling and heating. The DOE says you can save up to 20%.