Big cement pond done PIX

[koikeepr]

okay, koiguy can check my math here, but if your pond is 20 feet long and I'll use 6.5 feet as your average width based on your circles and stuff. Then with your max depth of 2.5 feet and your other area that is 1.7 feet deep, I'll use an average depth of 2.1 feet. I estimate you at around 2,047 gallons/US based on an oval or irregular size.

So:

20 x 6.5 x 2.1=273 then multiply by 7.5 to get gallonage=2047.5 gallons

That would mean that the 4,000 gallon pressure filter would work and would give you more filtration than you will need (to koiguy's point). You also will need a pump that can push push your water volume through that filter 1.5 times per hour for the best case scenario (no less than 2x per hour at worst). That would mean that you should get a pump that can push at least 1,350 gallons per hour.

I am not sure how much water pressure that filter needs to do the backwashing aspect (you should ask the seller). Sometimes they need a pump with very high GPH to do that properly. The trouble is, if you get a pump that pushes to fast, the water will go through that filter media quickly and may not build a good bacteria base. Ditto for the UV, if the water passes by too quickly, it will not do a good job as water passes past the UV too fast. In that case, you could get a higher pressure pump, but divert some of your water--like over the waterfall, perhaps.

Also, with that filter, you are able to use hosing from 3/4 inch all the way up to 1.5". If I were you, I would use the biggest hosing you can (in this case 1.5"). You will get much less friction.

All this being said, I think this filter will work for you if you get the proper pump. Again, that's all without knowing the answer to the backwashing question that you need to ask the vendor.

 

[DrDave]

This may not be the best thread to post this on, but this subject pops up everywhere.

I think the amount of bio filter needs to be tied more to the fish load than the overall gallons of the pond. Some people have a lot of fish and others, not so many. The concentration of waste needs to be considered, not just the total volume.

 

[koikeepr]

agreed. MMM did not answer that question after I asked it, but 150 inches of fish should be max. I just don't know if he's decided on goldfish versus koi or what.

 

[MMMxxxanaxxx]

Hey, thanks for all the help guys! Here is a link to a pump I already own, so I would like to use this one if possible
http://www.nextag.com/Flotec-3000gph-Utility-Pump-60118890/prices-html
The filter I had linked to previously was max 2700gph but my pump is 3000 gph. Do you guys think it would be a better idea to go with this filter so that I can use my current pump? http://cgi.ebay.com/5000-Gal-Pond-B...emQQptZLH_DefaultDomain_0?hash=item53dc5d6eb3

Thanks for the help

 

[koikeepr]

Hmmm...I'm not a big fan of using utility/sump type pumps in a pond, but I guess it will work. You can go with either of the filters you've showed us. As koiguy said, you can never have too much filtration. As long as the pump is properly sized to match it, you are fine.

Also, in reference to my answer above about 150 inches of fish, that should be determined at full growth length--not when you get them and they are 4 inch babies. In other words, a pond of your size, you should not get more than 6 koi (assuming a 24" maturity length). 5 would actually be better.