Raise KH?

[kaaikop]

Okay, I finally understood I needed to raise my CO2 levels, if I want to get rid of algea...
Right now I'm shooting for levels of 30-40 ppm. Here's the problem, I read several times that it's a not a good idea when your KH is low.
I'm getting a reading of 30ppm (~1.5 deg. KH). So I adjusted my pH monitor to kick in at 6,3, shut off at 6,1 (CO2 ranging 25-40ppm).
Where is the problem, too acid for fish? How do I go about raising KH?

 

[Purrbox]

Actually, there are several people running these higher levels of CO2 with a KH just as low, if not lower, than yours. Some of the risks that people where afraid of have proven to be less likely than originally thought. The biggest problem is that people who don't have a pH controller, often don't have a good way to measure the pH to ensure that they are getting the desired levels. There are a couple of ways around this. They can buy an inexpensive Pen pH Tester or construct a CO2 Drop Checker. The one allows you to read lower pH levels than liquid test kits, while the other allows you to test the CO2 levels with a set KH that is different than the tank. I wouldn't mess with your KH if don't have another reason that you would need to.

Also I'd adjust your meter so that it doesn't dip below 30ppm. It's fluctuations below 30ppm that encourage BBA. If you keep the levels about 30ppm, then the fluctuations won't encourage BBA.

 

[kaaikop]

Great, thanks!!! that's exactly what I was hoping to hear.
I'm also "overdosing" Flourish Excel since 2 days (read on a different forum that it will help destroy algea without killing life...)
dosing 50ml/day in 150G tank. So far no problem, fish not gasping for air, no mortality.
Actually (and this is new), my fish are really pecking at the algea, like if all of a sudden, it was tastier or something...
I'm talking about Platys, Swordtails & tiger Barbs.
I have really had it with algea, this is WAR!

 

[Purrbox]

The Flourish Excel has probably killed the algae enough that it's now soft enough for those fish to be able to eat it. Sounds like you're making lots of progress. Congrats!