I had a good idea the other day (it does happen).

If your like me, and made your tank before you really new anything about what you were doing, you might have gone for a pure sand/gravel substrate.. and then regretted it later on when you wish youd used something richer.

Well I had this idea, of how to get some aquatic compost into your sand, without creating a god awful mess all over the place in the process.


1) Make a thick gooey mud with the compost/whatever you wanna use.

2) Get a freezer icecube tray, and fill each section with the gooey mud, and pack it down, pretty hard.

3) Scrape off the excess from the top of the tray.

4) Turn out the tray onto a baking tray, might need some tapping to get it out, although I found the filling was heavy enough to just fall out of mine.

5) Bake the tray in the oven on a lowish heat for about 30 - 40 minutes. This will dry out each little square and set it rock hard.

6) Then all you need to do is push each nice little brick of solid compost into the sand/gravel. You need to be pretty speedy, as it will 'melt' very quickly.


and job done. This worked reallllly well for me, and because each brick is hard when it goes through the water, hardly any sediment is created.. therefore keeping the nutrients inside the brick as it goes through the water.

Be careful what you use though, if your a garden soil fan, boil the hell out of it first. Although I suspect a long slow bake in the oven will steralise it as wel.

Thats pretty cool Frolic... What was the mixture you used to enrich your soil? I wonder if it would be any better or worse of a technique if after you sterilise, you were to put it in ice trays and actually freeze it. Then you could insert it into your substrate where you like and it would thaw out in place.

yeah freezing would work too, maybe even better actually I just got some garden centre aquatic compost, which is very low in nutrients. Its quite gritty too, which I liked.

The mud cubes idea I got several years ago from a Kiwi.
Works quite well.

If you have a chance to do a new tank, boiling the mud for 10 min works well to leach out/oxidize any Urea/NH4 into NO3.

Freezing will not do that, it just helps adding soil to a preexisting tank.

You sort of ride the balance between adding too much/too rich nutrients and too little, but you can always add more/less later.

The problem is that it is very difficult for folks to test their substrate for nutrients.
They rely on the plants rather than any test kit or quanatification.

You can allow your soil/mud to dissolve in a DI water solution, say 5 grams in 100mls of of water and wait 24 hours. Take a small sample and measure for NO3/NH4/PO4.

Add 10 mls of Acetic acid, wait for 30 minutes, swirl etc good, then measure again.


Regards,
Tom Barr