To use an U/G filter or not?

[Mitsy]

Hello to all from the Pacific west coast! I am setting up my 29 gallon tall tank, and will be planting it heavily with plants, with fish to soon follow .

I have had conflicting suggestions on whether to use my U/G filter or not, I lean towards using it to help prevent anaerobic bacteria from growing at the bottom of the substrate, and this is how I construct my veggie filters for my outdoor ponds, a 'false floor' that creates space under the root mass to allow for good circulation. The roots actually grow down into that area eventually, where I would imagine they take advantage of the more concentrated fish poo anyway.

What's the general consensus with you more experienced aquarium folks?

[Caryl]

I have never had a problem growing plants over an UGF. Just make sure you have plenty of substrate on top - at least 2" thick.

Out of curiosity (after I was told UGFs are no good for plants) I once had a tank set up with an UGF over one half. I grew the same plants right across the whole length of the tank and could never see a difference in growing rates or health between those growing over the UGF and the others.

[Derek]

Like most things to do with fishkeeping there are no absolutes. That is there are usually more right ways that there are wrong ways of doing things.

With respect to UG filters. Some plants naturally grow in areas where there is an anaerobic substrate so it is felt that flowing oxygenated water past their roots (via a UG filter) is not a good thing. Other plants such as many rosette plants primarily gain most of their macro and micro nutrients via their roots, as such it is felt by some that a highly oxygenated substrate may oxidise some of these nutrients (especially iron) to a form that the plants cannot use. Whereas many stem plants acheive the same result via their leaves. The size of gravel to allow a UG filter to work at its optimum is larger than what is commonly described as optimum for plant roots.

I think factors such as these are often taken out of context and then extrapolated to the point where someone says UG filters are no good for planted aquaria. Like most generalisations, it is not always correct.

If you want to use an UG filter try it. Just consider the requirements of the particular plant species that you plan to grow just as you would for the different fish spieces. No tank will grow all speces of plants so if some die or do not grow then just forget that species and grow those that do. If you really want to grow a particular species you may have to fiddle with conditions until you get it to grow. One of those conditions may be the presence of the UG filter itself or it could be the flow rate of the water through the substrate. However, fiddling with the light levels, CO2 and supplemental fertilization are more likely to result in success than the mere abscence or presence of an UG filter.

[Ira]

Also, a lot of plants grow fine without having any soil at all, with their roots just floating in the water. If you've got a lot of nutrients in your water for the plants, and the substrate isn't very rich, say just plain fine gravel, then the flow of water past the roots could conceivably improve the growth of the plants.

[Paul]

I dont like U/G but then I like to have the option open to be able to substrate feed plants if and when needed, you cannot add food spikes around heavy root feeders like swords(Echinodorus sp) the rapid flow of water will send it all into the water colume and you will end up growing mass algae.

It is true that a good root system will oxygenate the substrate and keep it sweet any way.

Just my 2cents worth couldnt let this thread pass.

[Mitsy]

Paul, I think you have a valid point. concerning the U/G filters. As an outdoor ponder, the fear of anaerobic media is always forefront, but in an aquarium, I can see it being easier to control. I visited your website and was quite impressed! I notice you are using a finer size substrate than I have at present, I think I'm going to start looking around for something smaller, myself.

I am in a dilemma right now, as a mailorder supplier must have felt guilty about being out of a couple of selections I wanted so they sent a lot more plants than I had intended to get. The tank is now very crowded with plants, with a number of them going outside to be with the goldfish. I may still get rid of the U/G filter, as I am probably going to replace the substrate soon.

Will pond tabs broken into smaller pieces work in an aquarium setting? I am still trying to figure out how I can utilize our local lateritic soil into the substrate and not turn my water orange.

[Rob]

The way I've used laterite in the past is put a layer of it in the bottom of the empty tank, then a layer of gravel substrate over the top of that. Providing there are no fish that move excessive amounts of substrate around then there shouldn't be any problems.