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Fox River Koi
06-30-2015, 01:10 PM
I finished installing my DIY pressurized pre-filter this weekend.
I used a 14 gallon plastic barrel with a gasketed lid & metal clamp ring that I bought on Ebay. I would have preferred to use the larger 30 gal barrel but I just don’t have the space.
I installed three 2" bulkheads; 1 for the bottom drain, 1 for the inlet and 1 for the outlet/backwash. Both the inlet and outlet/backwash bulkhead are just below the "lip/ledge" inside the barrel which is where the eggcrate media screen is installed.

Fox River Koi
06-30-2015, 01:12 PM
The outlet/backwash pipe then runs vertically through the center of the media screen to a PVC lateral with holes drilled on the underside. I originally wrapped the lateral with 250 micron screen. Needless to say this didn't work very well as the screen clogged very quickly/easily.

Fox River Koi
06-30-2015, 01:13 PM
Once I removed the screen the flow was not an issue. I ended up adding more media (similar to K3) so that the top half of the barrel is basically full from media screen to the underside of the lid. Otherwise the water movement would move the media around leaving "voids" where larger particles could reach the lateral.

Fox River Koi
06-30-2015, 01:16 PM
I have a 3-way valve on both the inlet and the outlet/backwash. The one on the inlet side feeds a pipe that bypasses the pre-filter and goes straight to the pump. This served 2 purposes; 1-I can bypass the pre-filter if there are any leaks or other issues to contend with; and, 2-I need to bypass the pre-filter in order to backwash it. The 3-way valve outlet/backwash side goes to another 3-way on the waste outlet of the filter valve.
To backwash the pre-filter I turn the 3-way valve at the inlet side (sending the water flow directly to the pump), turn the filter valve to “waste”, turn the 3-way on the filter valve waste outlet to divert the water back to the 3-way valve on the outlet/backwash side of the pre-filter (and open the prefilter bottom drain valve of course). Man, reading that sure makes it sound a lot more complicated than it really is.

Fox River Koi
06-30-2015, 01:16 PM
So far I have had the pre-filter up and running since Saturday afternoon and I couldn’t be more pleased with how it is performing. Prior to Saturday, I would have to shut off the pump and pull and clean the primer basket every morning. It only takes 5-6 minutes to clean the skimmer screen, hydrosieve basket and primer basket but it bothered me the amount of algae that got past the hydrosieve. Most mornings the primer basket was pretty full and the water flow was slowed a bit. That also meant a lot of algae going through the pump and into the filter, albeit pulverized by the pump first.
I have not had to touch the primer basket and have not had any decrease in flow since installing the pre-filter.
Next week will be the real test as we are leaving for 10 days and the person who is staying at the house will only be checking and cleaning the skimmer screen and sieve basket while we are gone (unless there is an issue with water flow decreasing).

icu2
06-30-2015, 04:16 PM
Great job on the filter!
Like you said, usually time is the true test.

You're braver than I am as I try and change nothing before going away even for a few days...
but I hope it all works perfectly! :thumb:

Fox River Koi
06-30-2015, 04:40 PM
Great job on the filter!
Like you said, usually time is the true test.

You're braver than I am as I try and change nothing before going away even for a few days...
but I hope it all works perfectly! :thumb:

That's usually how I do things. LOL
I signed us up for our local pond tour 3 years ago 3 months before I completely tore out my 1,300 gallon, ground level, rock lined pond to construct my new 5,000 gallon, 1/2-below grade, 1/2 above grade exposed liner pond with paver retaining walls.
I though my wife was going to kill me but I finished with 1 week to spare. Did I mention that we took our vacation in the middle of that project as well.

Fox River Koi
07-15-2015, 12:43 PM
Well, the pre-filter did what I needed it to do while we were on vacation.
For 10 days the pond went without water changes, filter backwashing or pre-filter backwashing. The only maintenance that was done was the neighbor's kid rinsed off the skimmer screen, emptied the HydroSieve and fed the koi once a day while we were gone.
The average temperatures were in the 80's and sunny and we had one day with over 2" of rain. Needless to say, there was a bloom of string algae by the time we got back. However, the pump was running fine with a marginal decrease in water pressure due to the amount algae collected by the pre-filter.
I am going to experiment with using Bacti-Twist in lieu of the K3. The K3 backwashes fine except when left untouched for 10 days. :frusty: Then taking it out and cleaning it was a bit of a PITA. That's where I think the Bacti-Twist might fair better.

Primitive
03-23-2016, 06:15 PM
What was the flow rate on pump?
I want to do this using a 55 gallon and a 10000gph pump but I'm afraid of the drum getting squished by the suction of pump.

Fox River Koi
03-24-2016, 01:28 PM
This turned out to be a failed experiment.
Eventually, the pressure from filtering and backwashing caused the lid to crack.
I also found that the media did a pretty good job of pre-filtering; however, it did not clean well via backwashing as I had hoped.
I repurposed the media by putting it in the waterfall with an air disc at the bottom and a grate at the top to create a moving bed filter.