Making a simple water filter for a small pool

I am wanting to make a simple natural filter to get back into action my son's 8ft pop-up pool for the New Zealand summer.  (After we make a tub into a pond and relocate the frog in it).  It is 2,300L (600 Gallon) capacity.    
https://www.thewarehouse.co.nz/p/bestway-fast-set-pool-set-8ft/R2455691.html#q=bestway+pool&sz=24&start=25

I have easy access to river sand, gravel and stones.  Our hottest summer month has an average high of 23C (73F) so it will live inside a home-made greenhouse with lots of stones for thermal mass, and the water will be heated as well.

I am considering three options:

- a simple sand filter

- a basic aquaponic set-up, with heat-loving plants like capsicum - as the water we pump through its roots will be heated

- A water cascade with water plants in them similar to grey water tank filtration (hence this forum but feel free to cross-link if you know how or where)

Which would be best - or should a do a combination of all three, and if so in what order??

Any suggestions or links to really easy ones??

Hello Annie, it's not clear to me, you're going to set up this 2300 liter tub in a green house and put a frog in it? What for? Why only one? Lonely frog will want out. Why heat the water, frogs are fine with 23 degree celcius. What plants will grow in there. If you've got plants growing in there and frogs, maybe an air stone by itself will keep the water clean. If not, the three options you mentioned might be necessary. Hope this helps.

No - my son's pool that got abandoned during a family emergency for a few years currently has a frog living in it.  I have an old cement laundry tub moved into position that I will set up as a frog pond so the frog has somewhere to go, and then we will turn the pool back into a swimming pool for the New Zealand "summer".  

Aha! That's sweet, frogs are not very picky, but if you want a nice pool with clean water so you can see the frog you don't need a lot of extras you proposed. Just add a nice local selection of oxygen producing waterplants and create levels of depth. Plants grow at different levels. If you move the pond into the greenhouse, is that for winters?
Because 23 degrees in summer is good enough for frogs. The warmer the water the more evaporates. And algae bloom are more likely. I've had a pond for years, frogs came and started making noise in the night. I added fish, because i read female frogs don't lay eggs where fish are in the pond, because the fish will eat the offspring. So the older and younger ,less noisy frogs are in my pond. The fish eat musquito larvae and some off the plants. Don't get Koi, they eat all the plants. With this set up, small fish frogs and plants i kept the water clear happy and vibrant for years. Because it was quite a deep hole in the winter it didn't freeze completely, the earth never freezes at 60 cm and keeps nice and cool in summer. And i have willows around the pond. This year the fish got big, 20 cm, they added more waste to the water and that made algae bloom. Then i took care of that. It's a lot of tweeking to have a nice pool. It's worth it, i find, but if you don't have that time / interest and want to help a frog, just dig into the earth a 150 liter barrel in a shady place, add some oxyginizing plants and keep it tupped up with rainwater preferably.

Great ideas so far. Did the swimming pool have a pump or was it static? The sand filter idea seems workable. Aquaponics needs fish food to operate though.  You probably already know you'll need  a pump in the the system to get a sand filter to work. One question that comes to mind is what are you filtering out if there isn't fish in the small swimming pool?
You might want to peruse Australian Joeblow's thread  on Backyardaquaponics Joeblow's BYAP thread  he has something  called a Pond Sucker which appears to be available over your way. This is a garden hose attachment which sucks water out of pools. Yes it uses water to do this, but you can direct that water to garden beds.
Brian
 

Hi,

I am basically wanting to make it safe for swimming without using chlorine.  So basically I am trying to turn a round plastic pool in to a small natural pool.  I am mainly wanting to sift out any nutrients carried in that  make grow algae, and also sift or balance the dangerous bacteria.

Natural Swimming Pool.
-Need a Pump
-Need a Natural Filter

Pump
-I wonder what the flow rate has to be

Natural Filter
-Aeration
-Sand Filter
-Green Filter

Green Filter
-Maybe a mulch pit with Oyster Mushroom+Wine Cap
-Some people just plant half of surface area of the pool with aquatic plants.
At the end of the day we are trying to emulate a reed bed/wetland system

Thank you for the extra information Annie.
Have you set aside energy to run this little system? If so will it run on house power or photovoltaics?

Halloween-snow-2018-kio-pond-hugelkultur
Ours runs on a extension cord and has a small 110VAC pump as well as a small UV sterilizer for removing mobile algae.
One could run a small 12DC pump off a small solar panel during the sunshine it will circulate water through a filter.
Small DC pump
With the small pump you might consider pumping pool water up to a raised filter barrel and let it gravity feed back to the pool.
That reminds me, you should decide whether you'll have a pump in the pool or  make a bulkhead connection in the pool for a drain and have the pump externally mounted.
I hope this helps.
Best wishes
Brian