Thank you for your question. The Pondmaster Submersible UV Clarifier would have to be connected to a pump so the water can flow through it.

Thank you for your question. The 10W clarifier comes with 3/4" barbed fittings for the inlet and outlet.

Thank you for your question. The pump needs to be on while the clarifier is running to push the water through.

Thank you for your question. Both products are rated for a pond that is larger than the pond you are working with so they should work fine for your application.

The instructions that come with the clarifier say the water in your pond should circulate through the UV every 2 1/2 to 3 hours. Slower times will sterilize as well as clarify the water, but too slow and it may not keep up with the algae growth, too fast and it will not have time to kill the algae as it goes through the UV! You choose 20w or 40w based on size of your pond (L x W x D x 7.5) Then choose your pump by how many gallons per hour (GPH) it pumps so that your pond volume goes through it in the correct amount of time. I myself went for larger pump and larger UV wattage than the actual volume of my pond required. I figured it would be easier to get an adjustable pump or install a valve to adjust the water flow to the UV if needed than to not have enough of either. Also keep in mind the hose specs required by the UV Clarifier when purchasing a pump!

The sleeves are hard to get. I found one elsewhere but it turned out it did not come with the rubber end which you almost always must have. I found that a vinegar solution soaked overnight it a great way to remove crud from the outside of the tube. Should not need replacing unless you break it. If you do have to replace it you'll have to pay the high price the manufacturer charges so you can get the rubber piece. Make sure if you buy one the rubber piece will be included, because many times it is impossible to get the old one off the old tube.

Thank you for your question. Yes, you can use the uv clarifier in saltwater. You will need to remember to clean the sleeve with vinegar and water (50/50 mixture) every so often so the uv continues to work properly.

I have 4 of the 40 watt units so am familiar with them. It glows a green color (used to be blue but now is green) but is hard to see during the day. Check at night, it should be obvious. If you don't see it at night, unplug it and pull it out for inspection. Sometimes mine have an issue with the bulb just slightly slipping out of connection. This happens when I'm installing it and I bump it too hard sometimes. Be extremely careful when you remove the clear tube as it is super fragile. Don't try to pull the rubber fitting off the tube, just leave it in place if it is there. Some of them hold tightly to the quartz tube and some don't but pulling on it will break the tube as I found out. . Double check the bulb is very firmly in this socket in the only way it will fit. Then in a somewhat dark room test it out after fulling assembling the unit, being careful not to allow your eye to look into the openings as UV light is dangerous. You should see the light glowing in the halo rings, assuming you've assembled it properly. If you don't, you may have a bad bulb.

With all uv clarifiers you should be able to regulate flow by some means. This means you should not run this inline, but rather steal flow from the main pump by T-ing off of it and putting in a separate shutoff. You can then return the out to the pond or waterfall box. Im sure you local hardware store can help you find the fittings you need if you supply them with the measurment and materials of your exsisting setup. Of course if your pump flows at or below the minimum flow rating for the unit, inline would be fine. in that case just cut the exsisting hose and connect uv with proper connectors and couplers. Again, your hardware store can help if you tell them what you dealing with. Hope this helps.

Thank you for your question. The Pondmaster Submersible UV Clarifier/Sterilizer you should use for a 2000 gallon pond is the 20W - item # 74039.