Backyard Aquaponics
A place to discuss aquaponics

Hi everyone out in aquaponics land.I am a total newbie to the world of aquaponics.My problem being growing bed media.I live on a limestone island ,Grand Bahama.All we have is limestone pea rock and beach sand.Plenty of conch shells on the beach maybe I could crush them.Might be able to get some rockwall,but no river pebbles or expanded rock.Looking for suggestions on what to use or how to use what I have . Can I adjust the PH of the limestone rock and limestone well water in a inexpensive and all around safe way.I look forward to your guidance as I embark on this new adventure.











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I don't suggest trying to change the pH of something full of limestone. Kinda a loosing battle.

My media is totally full of shells. My system pH stays between 7.6 and 8. I am not the only one running like this however, the people that seem to be doing better with it than I, have lots of steel or iron rebar and other steel or iron bits buried in their media. As my system is maturing and I am adding chelated Iron to it more often, things seem to be growing better even with the high pH.

I would go for the shells more than the limestone if you can since I think they tend to buffer the pH to 7.6 instead of higher. My well water is what tends to bring my pH up near 8 but that is a temporary thing.

Make a small system with shells and see how it goes. If you can get hold of some reobar / steel off cuts, bury them in the shells.

I reckon the first thing you should do is get some possible growbed mediums and put them in buckets with the water you will be using and measure the pH after a week or month and see what is happening.

Other posters have more knowledge of these things than I though and that might be why they haven't suggested this

Is what I plan to do.... I live on "Limestone Hill". Just leave my local pea-grade growmedia in a bucket... over time test...then put crystals that I have into the bucket... test again.

To protect my pipes to the house from calcium buildup I use a product from this company...http://www.aquamat.co.za/. They are crystals I put in a pump prior to the water entering my system. When I do not use them the calcium buildup is phenomenal!... can see it in the kettle easily. Boiled water removes clacium. With the crystals there is no problem and even buildup is removed. I have not been able to establish what these crytals are.... just know they work. Can even be recycled a couple of times by drying out and breaking off the calcium crusted on them and put them back. I will probably have to do the same for my AP system. Currently my fish are doing fine outside of this system in untreated water. Acclimated. It is plant nutrient uptake I am most concerned about. My garden seems to do well.... but often irrigate from the house supply... so maybe that is why. There are plants that love alkaline... lavender... I assume mulberries... etc... and my tilapia did acclimate as already said.

This here is the actual product I use...http://www.aquamat.co.za/index.php?page ... calers.htm

I keep researching ways of correcting alkalinity. In agriculture they add elemental sulphur.... converts to sulphuric acid with large release of CO2. I don't want to experiment with this or Hydrochloric acid ....like in our swimming pool....on my fish water!

Thought I would add my input in case you can find something similar in your part of the world Hedley. How do you protect your pipes against calcium buildup?

Hope this helps some. If I learn anything more on this topic I will let you know.

Do you have access to quantities of coconut husk... husk fibres or chips... aka coco-coir?

It tends to run to pH 5.6 - 6.5.... could perhaps be used as a growbed media... and balance out your source water.... just make sure you thoroughly rinse any salt water off it...

Normally I'd steer away from using it ... as it holds water and stays wet for too long... well at least here in our climate...

Given your climate/heat... it might well be manageable... even if you only "flood" it once or twice an hour...

Many thanks people for all your suggestions. Tried breaking up conch to make crushed shell. I now realise this is not practical ,the little are too hard.Coconut husks available yes but not plentifull.What I have done is used the shells in the bottom of my barrelponics setup,for drainage ,on top of shells is a layer of plastic soffit with the vent holes .on top of this stands the pots with tomato seedlings in the ,lets see what happens.

Some1 was trialling using bottlecaps as media, if I remember corectly...
there is no requirement to use any kind of gravel I would think, only to have a media that plants can get roots around in easily.
Have a good look round, and see if there are any weird alternatives you can think of...
Small and porous is the best you can hope for.

Think that was Damien... "Carribean Grower" ...

Bottle caps are slightly positively bouyant, so if you were to use them they would need to be covered with heavier media. CG was using them as a bio filter.