Aquaponic Gardening

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Hi everyone! This is my first post here. I have a very green swimming pool that is roughly 20k gallons kidney shaped and has not been in service for 4 years. There is a good amount of sediment at the bottom that I have been removing by way of pool net over the past few weeks and it appears that I am making progress. I would say that 90% of this is dead or dormant algae, and the water as you would imagine is quite green. There are mosquito fish in there that have been happily living and reproducing for several years (and controlling mosquitoes effectively)

I have convinced the owners of the pool/pond (my parents) that the best thing to do is to create an oasis using natural methods and the like, and they are onboard so long as it doens't cost too much or become too much in the way of maintenance.

Some more relevant info is that we have a very steep slope above the pool as well as some area below the pool, either of which could be used for growbed/sump areas.

My idea at present is to pump the water from the skimmer up to some grow beds on the slope (southern facing) and then cascade this water back down to the pool perhaps through a solar heating panel and/or a uv filter.

Here are some questions for you all...

1. Will I be able to remove the algae without draining the pool? I am dilligently working to remove the scum from the bottom and I believe that I can get most of it, however, I am unable to stop the individual cells from going back into the water through the net, and at some point it will be necessary to kill it (shock with bleach) or UV filter it or something. The plan right now is to get as much out as possible, and then shock everything to kill all the algae while constructing the beds etc. The reasoning is that we cannot afford to crack the pool from groundwater if we empty it, and it is very expensive to refill it if we empty it. What would you do?

2. Does my plan to use the slope make sense? How much media will I need to filter this much water? I am thinking that I can construct some grow beds that are individually plumbed and feed directly back to the pool, or make them go from one to the next all the way down before flowing back. Is one design better than the other? Keep in mind that in the end we plan to have minimal fish for the purpose of controlling bugs and algae (tilapia or cats?), providing some fertilizer for the plants, and maybe some pretty ones for looks/eats. We do want to swim in the pool during the summers.

3. There is an existing sand filter. Is this useful in any way?

Thank you! Any and all comments/ideas will help greatly. I am curious about the UV filters especially at the moment, and any experience anyone has had with this type of thing.

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I agree that right away, you need to get some bucket of bin type filters going to help clean the water.  Since you are not going to immediately have enough grow beds to really handle filtering that much water, some form of cleanable filter should be set up.  If later you do eventually manage to set up enough gravel beds to handle the whole pool, you can always pull out the filter bins.  Those gray brute trash cans that come in various sizes would make good filter bins.

Plecos are only going to eat surface algae off the sides/bottom of the pool, they are not filter feeders.  To get rid of green water you need filter feeders but your best bet to get rid of green water will probably be filtration plus perhaps some barley straw extract.

The debris down in the bottom of the pool isn't going to change unless you can keep the leaves from falling into the pool and other stuff from blowing in.  A pool vacuum may be a helpful tool for sucking out the leaves and debris that don't get caught by the skimmer and pump basket.

Hey guys,

I will be constructing a filter or many filters, i have to figure out how to make it, where to place it, and how to camouflage it. Thank you so much for your help in describing these filters. Since I am making this forum partly so that others in my boat can get the advice that they need, I will suggest looking at "DIY pond filters" or "KOI pond filters" on youtube, lots of designs with all being the same general idea.


1. Barley straw creates hydrogen peroxide that kills the algae, why not just pour in some hydrogen peroxide from the hydro shop @35%?

2. Filter feeders, pretty pointless i think... unless there was a separate tank for them to live in that had the water flowing through it. I was thinking mussels, but it seems like more trouble than it is worth, but would be pretty cool to try.

3. Underwater plants, One of the varieties of plant that I got elodea or anacharis lives entirely underwater, i am wondering if anyone knows a good way to anchor the stems so that it will stay in one place and not float all around especially to the bottom where i will be sucking it out...

4. UV filter... I am very impressed by the uv filter's ability to clear up water without killing all the bacteria in the biological filter/growbeds. The problem is that they are so expensive for my size of waterway. I found a knockoff on ebay, the seller has lots of good ratings. How important is the "wipe" function on these, will i be cleaning it all the time? What are the odds that this works half as well as a $2,000 model? it is $420. I am very curious about this if anyone knows. I have emailed some of the buyers to ask them as well.

you'll be better served with mechancial filtration for removal of solids.. this may help with some "algae" in the water, but imho, it's not worth using in an ap system

Well Nik...

It appears you are determined to spend money instead of fix your real problem:

standing water that needs to become a flowing ecosystem with an animal and plant ecosystem filtered through a mechanical filter system. 

So far TC, Keith and I all agree;  you need to filter the water.  We have done this ourselves.  We have dumped too much money into a hole filled with fish and water learning the hard way that this does not need to be reinvented.

Go back to Step 1 -- IT Works! 

Then Step 2 -- IT Works too!

so far we have determined:

1. water quality is okay

2. water is not moving

3. there is (undesirable) stagnant water plants growing in the stagnant water (doh)

4. system has existing power and pump

5. flowing water changes everything

6. stagnant water plants get caught in filter when moved by current

7. herbivore fish eat plants

8. goldfish are herbivores

9. goldfish are $20 per 100

10. goldfish are pretty and grow fast

11. filter box at walmart $15 bucks

12. fittings at Home Despot $10-20 bucks

13. 1-1/2 pvc pipe -- $1/ft at Home Despot

14. coco grow mat for filter available at:


Marin Hydroponics
55 Frosty Lane
Novato, CA 94949
(415) 233-4104

Open Monday-Saturday 10AM-6PM


Marin Hydroponics #2
721 Francisco Blvd. East
San Rafael, CA 94901
(415) 482-8802

Open Monday-Sunday 10AM-6PM

There is no reason not move forward on this project if you have access to:

1. 1 afternoon

2. $100 cash

3. knowledge

4. talent

read, learn, do

all the best!


Thank you keith,

I noticed that lots of koi people use it to keep the water clear. Part of the requirement of the folks is that the water not be green. This will be a last resort after setting up a settling tank, a mechanical filter, a biological filter, and some grow beds.

Other input is appreciated.

Yep first step is get the water circulating and going through some filtration (filtration can be as easy as stuffing materials like screen, netting, shade cloth, scrubbies, filter pads, even plastic drink bottle caps into a bin of whatever sort and flowing water through it.

Once that is running you can think about a UV clarifier if you still really want to spend the extra money.  Keep in mind that the UV stuff is sized by flow rate and your flow rate needs to be sufficient for your water volume in order for it to be effective.  Do lots of reading and research before you buy.  Keep in mind that the UV clarifier will only be effective against free floating algae in the water, it won't do a thing against surface or string algae.

I believe there is more to the barley straw extract than hydrogen peroxide.  Yes hydrogen peroxide can work against algae but hydrogen peroxide can also kill your fish and bio-filter bacteria if you use too much of it and I expect if you use enough of it to quickly have any effect on algae, you will have probably used enough to injure fish and bio-filter bacteria too.

I can wait to see how the biofilter works on a pond this size.
Any progress?
I gave up waiting and moved forward on my own pool to pond project. I cannot believe how fast these bio filters cleared the water up. I did 3 things. I added a 110L air pump, pumping to 4, 4" round bubble stones witch churned the water from being green to being pea soup. Those have been running for four weeks and 2 days. 2 weeks ago I covered the entire deep end of the pool with a thick blue tarp I got from harbor frieght for $29, and then built 2 42 gallon bio filters with coarse evaporative cooler pads as the meida , and 2 32 gallon bio filters with fine evaporative cooler pads in series after the coarse filters and they drain into a 25 gallon filter full of lava rock and that drains back into the pool. The pump running them draws from the bottom of the deep end of the pool and drains into the dead center of the shallow end of the pool, where I have 4 Lillie's and 3 other pond plants. I can actually see the bottom of the shallow end of the pool now with is 4 foot deep. If I could figure out how to post pictures from my iPad I would post pictures to show the progress.
I forgot to mention that as a gag about 4 years ago I put koi and gold fish in the pool, and they have been happily multiplying the entire time. Now I would say I have well over 100 in there now. The ammonia levels are still off the scale but I am sure they will begin to decreas over time.

Very cool Jeremy!  Glad to hear the evap cooler pads worked out so well for you.

Your ammonia will be high until you have a plant load.  Pond plants work good for a start, but veggies like lettuce, green onions, etc. will really help to get things under control. I am growing bushes, trees, veggies, bamboo, duckweed and flowers in my raft and container bed at this time.  Everything seems to work well and much faster too.  Radishes sprouted in 3 days instead of 7-14 days stated on the package!

Doing something is always better than doing nothing.

Keep the faith!


Actually Jim, I would expect the ammonia to drop as the bio-filter establishes it's self then nitrite will rise then drop as the next stage of bacteria establish and finally nitrates will rise until veggies can start consuming them.

Pond plants will often consume ammonia directly though as can algae and duckweed.

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