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The Natural Aquarium, 6 Soils and Substrate
Swimming Pool Filter Sand As an Aquarium Substrate
One More Test: Would Sand Alone Work?
Here was another crazy idea.
Gravel has been the mainstay of aquarium keepers for nearly one hundred years partly because it can be cleaned easily. With under gravel filters, you draw aerated water through the bottom and break down detritus aerobically.
Let’s test this to find out.
It did work. Plants grew somewhat slower, but still faster than I needed. The water was clean and the aquarium looked great!
Any plant that covers the bottom shields the eyes from excessive detritus, the anaerobic bottom allows the plants to have the ammonia they need, the aerobic open water area takes care of any excess nitrogen in the tank and now, I change my water once or twice a year.
This little trek had taken more years than I care to tell you, but now I can present to you a simple, lazy person’s method of keeping an outstanding tank.
You may note the leaves in the images. Don't do this unless you are young and like the extra work. Yes, the pants loved it, but when you pull out a rooted plant you generate a lot of detritus.
Mulch in the tank? Yes! Hmm, NO!
Loren Nancarrow, a local TV personality and I had talked about Humic Acid on his radio show and all three kids had entered and won awards at the Greater San Diego Science and Engineering Fair for work on humates and humic substances. There is a segment on humates later in the book, for now let’s just say they are the organic remains in humus. They make plants grow faster and they inhibit algae growth.
Sadly my friend Loren is now gone.
I was using gravel at the time without the under gravel filter because anaerobic bacteria (without oxygen) in the substrate make ammonia and ammonium from the nitrates and nitrites in the tank from the fish. Also, in an anaerobic substrate, the organics make CO2, which the plants thrive on.
So while the family watched Loren’s weather cast one night (back when he was a weather person, now an anchorperson) I was putting mulch in my fish tank. Loren was putting mulch in his garden.
MULCH? Are you crazy?
While I can’t answer that question directly, my mother always thought so. . .
While my brother played baseball, I climbed cliffs, then rocks, and so on, so it is a valid question.
OK, call me crazy, yes, those are collard greens and leaves from my garden along with the mulch, I didn’t want all of it to break down at once, but the typical gravel thing wasn’t going to work with mulch so I used sand over the mulch. It made sense, that is, it was a logical step.
We had started experimenting with fermenting leaves in water to make humates and my son had already proved this was an algaecide (See Appendix 1) as well as a plant fertilizer (yes, it is selective it kills only algae and fertilizes every other plant we tested including bryophytes), so why not make the humates right in the tank.
Unfortunately, the sand I used was also from Home Depot. I should have gotten it as I have since then from the Swimming Pool Supply Store. It was dirty but eventually settled down. The plants grew at unprecedented rates. I started using aquarium plants in my mulch pile every week. The output was extreme. The photos of this particular tank did not turn out well because I used the wrong sand.
Do not use unwashed sand in a tank, you will have a mess.
I commented to the on-line groups about this and, never owning a swimming pool, didn’t know about the clean sand they sell there as a filter medium. I had seen fluidized sand filters in the aquarium shops but didn’t think about this as a source for my substrate. Later I changed to swimming pool filter sand and we were there.
About this time I hear of the quintessential plant guy in the world, Takashi Amano. If you every have the chance, at least look at his books, if not buy every one you find. He is an artist with his aquarium designs and in his photography.
He started dumping carbonated water into his tanks to increase plant growth, and developed CO2 injectors to increase plant growth. I tried this and it worked! Within an hour the plants were giving off streams of oxygen bubbles.
I dumped some carbonates water into the tank, and that worked, I played with potassium carbonate, sodium chloride, sodium bicarbonate (baking soda), magnesium sulfate (Epson salt), iron compounds, trace minerals, humic acid, tea, and other things for fertilizer, bone meal, blood meal, all with good results, but again, don’t bother unless you actually want to sell plants.
Yes, the plants grow faster, but again, too much work (or expense) for too little payback.
Amano also used fertilizers. His tanks are pristine because he changes water daily, and you can’t argue with success, unless you are, like us, lazy aquarists.
I don’t care if there is a little detritus on the bottom of the tank, I have so many plants it really doesn’t detract from the views.
The mulch idea was tested in three tanks and worked quite well. Then I found a book on-line titled Ecology of the Planted Aquarium by Diana Walstad. This is a good book if you like detailed discussions of various aspects of what you are reading here. She does a very good job of research and presentation.
Walstad recommended actually using soils in the aquarium. So, again, with only one tank I reworked the aquarium added a layer of mulch, then soil, then sand to keep it all down. This was a lot of work for a lazy guy like me, but again the results were really quite good as long as you don’t disturb the bottom. If you do, you have mud.
The trouble was, the plants grew so fast, you had to thin them out and this disturbed the bottom. The Cryptocoryne I was growing was supposed to be 6” tall, they were 16” tall and propagated like crab grass.
I was now growing plants that were “slow growers” like Cryptocorynes by the handful. I would sell so many to the plant stores I was driving down the local price for these plants.
No, I am not kidding.
When I took them in to sell them, the mass of plants was a solid block and we broke it into several hundred plants and the shop sold them for twenty five cents each, normally they sell for $1.25 or so at that time.
On top of that they grew twice the size they should have been. People misidentified the species because of their size. The plant them only to have them revert to the smaller size!
It was magic! (Root word, magi like those in the Christmas Story.)
The Ambulia (left side of the tank above) grew in all directions rapidly. Again, more mulch from my organic garden.
So much for soil, unless you are not lazy and like reworking your aquarium one a year or so.
We seemed to have all the pieces together. We had organic detritus from the plants and fishes to feed the bacteria and recycle the materials, carbons compounds, nitrogen, phosphorus, potassium, trace elements, sand alone should work and using clean sand from the swimming pool supply shop would produce a bright white bottom.
OK, let's save some time and grief: Without a substrate cleaning snail such as the Malaysian Trumpet or Cornucopia snail, the substrate will turn black from fungi. You will need these snails.