Pond Boss Forums AERATION Systems questions Rotary vane and a timer???

I have a couple 1/4hp Gast rotary vane compressors. I understand these are for continuous duty but how bad is it to run them on a timer? I have them set to run from 11pm to 9am right now. Am I gonna kill the pumps? Should I set the run time longer?

I'd like to try some perch in the fall so I'm experimenting with DO and temperature to see how it runs this summer. I don't want to cook the pond or my parent's electric bill!!

Thanks in advance
Chuck

Running on timer is not a problem, try to keep back pressure under 10 PSI,( if low pressure model ) The lower the pressure the longer the pump life. Ted

ChuckC - Ted gives good advice. The start swithces on the Gast compressors are durable and will easily withstand the daily on-off cycles.

1. HOw big is the pond, 2. what type of diffusers and 3. how deep are they located? You may be able to run the aerator for less time each day. Monitoring your DO and temperature will tell you if you are mixing adequately. There should only be a difference of around 4F to 5F between top and bottom.

Ted - Pressure is running about 7-8psi

Bill - You were kind enough to e-mail your perch articles to me in March. A quick review of my post: Babbling post should answer some of your query. Diffusers are currently about 15-17ft deep in both ponds. They have been in since Memorial Day.

First DO/temp reading taken via boat this season in the larger pond. The breeze was moving me around a bit so the probe was not real steady but the readings s/b good enough for my purposes:

6/7/06 1:00pm 78F Sunny - I understand time of day will make a diff on DO and will take some in the am/pm as the season progresses......

Depth Temp DO DO SAT
1 75.0 7.30 86.9
3 73.8 7.39 86.2
5 73.2 7.45 87.1
7 72.9 7.69 88.7
9 72.5 7.51 88.0
11 72.3 7.50 86.3
13 72.0 7.33 84.6
15 71.8 7.17 82.3
17 71.4 6.03 68.6
19 71.4 5.29 60.5
21 69.6 6.02 66.0

Not sure how to make the table work but I think it can be deciphered. The 19ft DO reading is suspect.

If I could get away with running the pumps less and the switches will survive that would be great!!

Thanks in advance for further comment/insight....

Chuck

Chuck,

Isn't that a little deep for a rotary vane?

Something no one has mentioned yet that you may need to watch out for in Michigan if you cycle your pump is freezing up during the winter. I had to make sure that my air lines drained well all the way down into the pond so that water would not get trapped in the line above gound/water where it would freeze and plug the line. Also, I use a Thomas pump, they recommend you install a heater on the pump housing so that condesation in the pump doesn't freeze the vains and break them on startup. I have so far found this unnecessary. I used the heater the first year but have taken my chances since then. No problems yet. I've never replaced my vanes in 5 years of running 8 hours per day.

ChuckC, In SE Michigan you should not have to run your compressor in the winter if you keep about 20%-30% of the snow of your pond. If you do this then you eliminate all the problems of runing the compressor during winter. Don't let complete snow cover lay on the pond for longer than 2 wks.

Cecil - It's at the upper end. Recommended 18ft max. I made sure when putting them in to not go over the 18ft mark.

BZ/Bill - Have not run the pumps in the winter for the past few years prior to the renovation. No problems.....I like to skate so clearing surface has/will not be a problem.

I guess I come back to the question....more or less run-time duration?? I'm thinking I need more data(the whole summer) to make that determination. I'm wanting to find out how the depths beyond the diffusers are affected...if at all i.e. is there any mixing occuring. Any more thoughts???

Personally I've come to the conclusion that aerators put air into the water by moving water and exposing more of it to the atmosphere at the surface then they actually put in through the air bubbles. Then of course they can help circulate aerated air to other depths. I took the approach of putting my aerators in the deepest spot and running them intermittently to save energy during the summer and avoid super cooling in the winter. If you aren't running in the winter then the only reason not to run 24/7 would be to save energy. Wish I had the benefit of a DO meter. I would think you could establish a reasonable schedule for your aerators and start checking DO throughout a 24 hour period. If the DO stays high then cut back on the run time. I chose to run mine from midnight to 4am during the traditional low DO period and again from noon to 4pm thinking that this also could be a low DO period during the heat of the day. Don't know if my logic is sound but it has worked for 4 years and I only run 1/3 of the day to cut energy bills.

ChuckC From your June 13th data it looks like you are getting fairly good mixing to the bottom. Do a few more tests when the water gets near the 80F mark. This will also give the bottom water more time to consume the dissolved oxygen. So if you are not adequately circulating the bottom water the DO will be lower than those of the current readings.

I'll check back as more data is available. I'm really interested to see if the depths beyond the diffusers will remain "useable."

ChuckC - Do you have a date and surface water temperatures for starting your aeration for the 2006 season?

Bill - The diffusers were placed on 5/29. The run time was limited to 4hrs in the mornings for about 5 days. The timers were installed and went to the overnight run. The readings were taken on 6/7. But alas...... I did not think to take temp readings immediately prior to start up.......oh well......

I did take some sporadic surface temp/DO readings in April/May. It was amazing how high the DO was.....10-11+ at that time!!

Chuck

CC - The late start of your aerator of 29 May, I think explains why the diffusers are not mixing real well below the 19 ft depth. As the summer and additonal aeration continues you should see a slow, gradual temperature increase at 21 ft. If you would have started you aerators sooner (late April) then complete mixing should occur at all depths when diffusers are located at 17ft with your current run times. Additional measurements, this year and next year, will tell the rest of the story. Keep us informed about your tests.