If I set up a tank and used lava rock and an airstone with an air pump in place of a mechanical filter, would the tank support fish if I just performed large, weekly water changes? The reason I ask, is the bacteria would just grow in the lava rock instead of the filter media. And, the water change would remove dissolved fish waste and the airstone would mix oxygen in the water.
Yes, this will work if set up properly and you don't go crazy with stocking or fall behind on maintenance.
Lots of folks try out the "Walstad Method" with varying degrees of success. You can look into that (if you haven't already) for ideas of how to set up a contained and fairly self-sufficient system that minimizes both equipment used and maintenance.
If you are working with a freshwater system that doesn't involve destructive animals, incorporating live plants will work wonders when paired with a responsible maintenance schedule. The more plants you have, the more biomass you have that is consuming things like nitrates, ammonia, minerals. As a nice bonus, live plants provide an amazing aesthetic to the tank.
If it was me, I'd toss the air pump and just get a powerhead/circulation pump. You'll have better water movement and oxygenation. Many folks believe the bubbles from an airstone are what oxygenate the water but it is really the surface agitation as they break the surface of the water that creates gas exchange. A powerhead or other type of pump that is angled towards the surface to create ripples is going to be much more effective and ensuring the tank is adequately oxygenated.
That being said, if you like the aesthetics of an air stone and can tolerate the sound of an air pump, by all means go ahead with that route. I just know a lot of folks don't like the hum/buzz of a lot of air pumps out there.
A biological filter is basically just a lot of surface area on which beneficial bacteria can anchor, and current to move water over said surface area. If you can provide that in some other way, there should be no problem. Even massive water changes probably aren't necessary, especially if your tank is planted.
Natural ponds and streams don't have filters; they have substrate that is slimed up with beneficial bacteria and other critters that take care of waste and keep the water liveable. The only reason aquariums generally require filters is because the stocking density is so much greater than a natural body of water.
My tanks are all Walstad-ish. I am fascinated by her method, but it requires a low stocking density. Since I like lots of fishies in my tanks, I put filters in them. But once the plants really get going, I'm pretty sure I could shut the filter off and the water quality would be OK.
I researched the Walstad method several years ago and tried it. The nutrients in the dirt were exhausted in just a few months and I had to use root tabs. Root tabs in a dirted tank is a mess. So, I found this method has a flaw for the nutrient reason. I set up a 60 gallon tank and used a couple of house plants to filter the tank water and the constant nutrients from the fish waste material caused the plants to overgrow.
I researched the Walstad method several years ago and tried it. The nutrients in the dirt were exhausted in just a few months and I had to use root tabs. Root tabs in a dirted tank is a mess. So, I found this method has a flaw for the nutrient reason. I set up a 60 gallon tank and used a couple of house plants to filter the tank water and the constant nutrients from the fish waste material caused the plants to overgrow.
ot
Which house plants did you use? Ambient sunlight or overhead light?
I used Chinese evergreen (Aglaonema). I believe these are the Gemini variety. Anyway, these plants used the nitrogen from the fish waste so fast, that the nitrite bacteria didn't have anything to convert to nitrate. So, nitrate was nearly zero. These plants will do fine in room light, but I hung a four bulb shop light above the plants. The combination of stronger light and constant nutrients from the dissolved fish waste in the water caused the plants to get much larger than normal. They're the size of a large beach ball.
I used Chinese evergreen (Aglaonema). I believe these are the Gemini variety. Anyway, these plants used the nitrogen from the fish waste so fast, that the nitrite bacteria didn't have anything to convert to nitrate. So, nitrate was nearly zero. These plants will do fine in room light, but I hung a four bulb shop light above the plants. The combination of stronger light and constant nutrients from the dissolved fish waste in the water caused the plants to get much larger than normal. They're the size of a large beach ball.
ot
Have you tried pothos? If so, are these better than pothos in the amount of nitrates being consumed?
Interesting about the soil petering out. I've never had that happen in my dirted tanks, one of which has been up and going for over three years. I find that the soil replenishes itself.
I like the house plants! I've always wanted to try that (I would call it a "botanical filter" because it sounds cool) but never have yet.
Yes. I tried pothos, philodendron, nephthytis and Prayer plants too. Their root systems were too small and the plants never grew large enough to make a difference in the level of nitrates in larger tanks. I suppose the smaller plants would work in a small tank. The roots of the Chinese evergreen have gotten quite large, to the point I can only keep very small fish in this tank. There's no room for a larger species.
I took the filter out of my 20 gallon, because it is nearly all live plants and only 8 tiny White Clouds, a few small shrimp and some snails. I don't have to change the water nearly as often, and it hasn't affect the quality, at all.
My main fear with the Aquaclear 50 I had on that tank was that it might one day leak while we were on vacation, and we would come home to a water-soaked mess. It never happened, but that was always in the back of my mind. It sealed completely, yet, I always dreaded that possibility, and besides that, I got tired of cleaning it.
I still have my air pump and 4-inch airstone, and get plenty of surface agitation.
I plugged up the filter opening in the lid by placing a clear piece of plexiglass over it and taping it down with duct tape.
If you can get by without a filter and maintain good quality, that's the way to go. Only experienced aquarists should try that, however. Newbies tend to overstock. I did, when I first started.
20 gal. high: planted; 5 white cloud minnows, 4 golden White Clouds, several RCS, 2 blue shrimp, 5 Amano shrimp, several snails; Azoo air. 65 gal: planted; 6 rosy barbs, 6 yellow glofish, 3 red glofish, 3 zebra danios, 5 white cloud minnows, 3 dojo loaches, 6 crimson spot rainbow fish, 12 large Amano Shrimp, several snails; AC110.
Keeping an Aquarium With No Filter
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Wels catfish
Originally Posted by oldtimer
