Hi Folks,
I'm looking to rebuild the legacy brushes-and-mats filter in my 3000 gallon concrete pond.
It was badly done the first time 7 years ago, no thanks to a combination of my inexperience, and a slipshod pond contractor.
The filter chambers are not plumbed to be drained, and purging each requires the use of a manually inserted submersible pump for each chamber. That is a lot of work, more water change than the fish would be comfortable with, and has resulted in me doing somewhat less maintenance than I should on the system.
Thankfully, the chamber separators in the filter section can be torn down without damage to the walls of the main pond. This is where most of the rework will be carried out in an effort to modernize the pond. The only work involving the main pond chamber will be the coring of a new 3" hole in the wall separating filter and main pond to accommodate a sorely needed gravity skimmer.
I am looking at installing a 4-tier single bakki system that is fed by a Ultrasieve III. Two of the three existing TPRs will be sealed off as the pond circulation will be considerably changed with the installation of the shower.
Here's a breakdown of the "before and after" as per my plans. Hopefully this will reduce the amount of maintenance needed on the system, and allow me to increase my stocking and feeding levels from the current barest minimum. Your comments are much appreciated!
==
Now:
4-chamber gravity feed concrete filter
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1st chamber
Contains: 30 Brushes
Input: 3x BDs
Output: 2nd chamber
2nd chamber
Contains: Japanese Mat
Input: 1st chamber
Output: 3rd chamber
3rd chamber
Contains: Hack and slash 50 liters K1 and 50 liters K3 in laundry bags (aerated by dedicated Hiblow 40); This used to contain more JMat
Input: 2nd chamber
Output: 3rd chamber
4th chamber
Contains: Tsurumi 50PU2.15 plumbed to 3x 1.5" TPRs; Oyster shell bags (aerated by dedicated Hiblow 40)
Input: 3rd chamber
Output: Pond via 3x 1.5" TPRs
Pond
Contains: 3 mature koi; 3000 gallons of dihydrogen monoxide
Input: 4th chamber; koi poop
Output: 1st chamber via 3x 3" BD (building foundations make for 3 distinct deep points in the pond - each BD serves one)
The BDs are way oversized for the flow rate and need constant and wasteful purging - hence my intent to ramp up the flow rate considerably in the redesign.
Planned:
External Ultrasieve III and Bakki with 3 chamber filter (Knocking out the old chamber separators and building new ones)
==
1st chamber
Contains: 2x Tsurumi 50PU2.15 plumbed to Ultrasieve III
Input: BDs; gravity skimmer; overflow from 2nd chamber
Output: Ultrasieve via the pumps; Overflows into 2nd chamber if the the Ultrasieve pumps cannot keep up with input
Ultrasieve III
Contains: Some Momotaro BHM stacked below the sieve plate (maybe)
Input: 1st chamber
Output: 2nd chamber via 3" (modified from 2") outlet under gravity
2nd chamber
Contains: Static K1, air line from Hiblow 40 for maintenance boiling, submerged UV lamp (on timer circuit, 4hr daily)
Input: Ultrasieve; overflow from 1st chamber
Output: 3rd chamber; Overflows into 1st chamber if the flow into the 3rd chamber is slower than the input from the Ultrasieve; Valved drain port
3rd chamber
Contains: 2x Tsurumi 50PU2.15 plumbed to Bakki and 1x valved TPR; Oyster shell bags (permanently aerated by Hiblow 40)
Input: 2nd chamber
Output: Bakki shower and pond via 1.5" TPR; overflows to drain port
Bakki shower
Contains: 60-80kg of Momotaro BHM in 4 single trays
Input: 3rd chamber
Output: Pond
Pond
Contains: 3 mature koi; 3000 gallons of dihydrogen monoxide
Input: Bakki shower; 3rd chamber via TPR; koi poop; trickle feed from water mains
Output: 1st chamber via 3x 3" BD and gravity skimmer (3" pipe to skimmer collector)
I expect the Ultrasieve system to move more water versus that of the Bakki since the former's friction and static head will be a fair bit lower than that of the latter. This should keep the solid tainted settlement chamber water out of the static k1 chamber.
Total water turnover should be about 4000 gph as per my calculations based on pump charts and system head estimates.
My main nagging questions are...
1. Will the bakki alone be enough biological filtration? My original plan was for there to be a moving bed K1 chamber sitting between the sieve return and static K1. Most materials I have read so far however indicate that the Bakki should be more than capable of handling my relatively small, conservatively stocked pond (only 3 mature fish at this time). Squeezing in another chamber would result in the filter being much tighter, and my thoughts at present are to remove it altogether if the 4 tier Bakki with 60-80kg of BHM will do the job with capacity to spare. A little voice however tells me that a separate biological system might be good to have in case I need to take the Bakki offline for maintenance.
2. About how large (in gallons/liters of K1) should I set up the static K1 filter given the 4000gph targeted flow rate? I do maintenance every weekend or two.
3. There is talk that less flow might actually be better than more flow for a bakki. Is there any truth to this?
4. Would there be any benefit to installing a second Ultrasieve in parallel with the first? 4000gph is well within the operating specifications of a single unit. I will be cutting out the 2" return to fit a 3" bulkhead in its place, and adding an overflow tube joining the top and bottom halves of the filter to guard against a blocked screen.
5. Finally... Do you see any critical flaws that need to be worked out?
Much Thanks,
DF