Change the  water (distilled only) and clean the filters on the sides of the chiller. The filters allow for air flow to help the heat exchanger work at optimum performance. If you are in a dusty environment, you may need to clean them more frequently. The water is changed to prevent Algae buildup. You should target changing your water every 3-4 months. If you do develop an algae build up, you will need to perform a system flush. 

Performing a System Flush (Algae or Contamination)

If your coolant has developed algae, cloudiness, slime, or a green or brown tint, the system needs to be decontaminated, not just refilled. Draining the chiller and topping it off with fresh distilled water will not solve the problem, because the growth is clinging to the inside of the tank, the hoses, and the laser tube's water jacket. The flush below removes it.

Seeing black specks or "floaties" inside your laser tube? This is almost always coolant contamination, not a failed tube. It looks alarming, but a tube does not need to be replaced because of it. Perform the flush below and the particles will clear out with the old coolant.

What You Will Need

• About 6 gallons of distilled water
• About 2 gallons of white vinegar
• A few drops of dish soap
• A bucket or drain pan for the old coolant

A flush uses considerably more water than a routine water change. The quantities above cover the 50/50 decontamination fill, both circulation passes, the clean rinse, and the final refill. Running short partway through and topping off with tap water undoes the entire job, so it is worth having the full amount on hand before you start.

Flush Procedure

1. Power the laser off and drain the chiller completely. You only need the chiller powered on to circulate during the steps that call for it.
2. Fill the chiller with a 50/50 mix of distilled water and white vinegar and add a few drops of dish soap. Run the chiller pump for several hours so the mix circulates all the way through the tank, the hoses, and the tube jacket.
3. Agitate the lines by hand while the pump runs. Working along the silicone hose, pinch it closed and release in an alternating rhythm, first one line and then the other. Each pinch and release sends a pressure surge through the loop that breaks up the film clinging to the hose walls and tube jacket. Steady, uninterrupted flow will not lift that film on its own.
4. Reverse the inlet and outlet hoses and run the mix again. Pushing it through in the opposite direction clears growth the first pass could not reach. Repeat the pinch agitation on this pass as well.
5. Drain and flush with clean distilled water until all vinegar and soap are gone and the water runs completely clear.
6. Return the hoses to their correct orientation. This is easy to forget after the reverse pass. The chiller outlet feeds the tube inlet, and the tube outlet returns to the chiller inlet.
7. Refill with fresh distilled water and purge the air. With the laser still off, run the pump and watch the tube jacket until no bubbles remain.

When pinching the hose, use firm, steady pressure with the flat of your fingers. Do not crimp hard enough to kink the hose or put strain on the barbs and fittings. If a hose has gone stiff or discolored with age, do not force it — replace it instead.

Do not skip the air purge. An air pocket trapped in the tube jacket creates a hot spot on the glass and can crack a tube that was otherwise perfectly good.

Keeping Algae From Coming Back

• Use distilled water only. Never use tap water. The minerals and microbes in it feed both scale and algae growth.
• Keep the chiller out of direct sunlight. Light is what drives algae growth in the tank and lines.
• Stay on your water change schedule. Regular changes are what prevent buildup in the first place, and they are far less work than a full flush.