Feedback requested on my outdoor planted tank
I have a 75-gallon tank that I set up on my outdoor covered patio last March. Having moved recently to our present, southerly location in Monroe, Louisiana from the north, my ambitious goal from the get-go was to make this a permanent outdoor planted discus and cardinal tetra tank. Now I knew I had some strong sticking points working against me from the very start, including the following:
1.) Many experts say discus and planted tanks do not mix-- both because discus require warm water (at least 80F for larger fish and at least 82F for younger fish), and because Discus are healthiest in substrateless tanks that can be maintained nearly dutreus-free.
2.) The summers are very warm in Monroe, with average daily high temperatures in the 90's for nearly four months of the year. Most planted aquarium experts know the great majority of aquarium plants will fail in water temperatures above 82F, and certainly above 85F. While this past summer was not exceptionally hot, there were at least a few weeks where the water temperature in the aquarium approached 88F. Of course this is nothing a chiller won't fix, but I've already sunk enough $$ into this setup, as you'll see later. And I cannot lower the temperature too much with a chiller given my aspirations for discus and cardinal tetras.
3.) The winters are quite cold in Monroe, with the average high/low temperature in the month of January being 57/35. Records that I found indicate certain rare cold snaps have occurred here that have brought temperatures as low as 4 degrees Fahrenheit! Low temperatures are just now becoming a challenge, with two nights this week having fallen to 34F. With two 150W heaters going, this lowered the water temperature from 80F in the evening to 74F in the morning. I have since insulated three sides of the aquarium tightly with 1" thick Styrofoam insulation and have replaced one of the heaters with a 300W outside-the-tank Eth heater which is plumbed to the outlet line of my canister filter. Also, I had some pieces of glass and insulation cut to fit the openings on the top of the tank, minus the areas where cords and filter lines enter the tank. My plan is to place the glass and insulation pieces on the top openings of the tank only on cold nights. All this should help maintaining the temperature of the tank, but I may still need to add a third heater to keep the temperature at 80F on the coldest nights in winter (I can already see that big electric bill).
So, given theses three huge hurdles that I needed to clear, I chickened out (at least for this year) with trying discus in the tank. Instead I decided to go with a school of 40 small cardinal tetras, a species which prefers similarly high temperature as discus. I told myself if I could get them through the extremes of a Monroe summer and winter, next spring I might splurge and buy four of the fabulous but extremely expensive discus varieties.
Now as many of you probably know outdoor aquariums aren't all problems, and can actually have some big advantages. You don't have to worry about spilling during water changes and I can just siphon directly to the flower bed. From previous experience with low-tech outdoor tubs, I knew that for some reason fish raised in tanks exposed to the outside air often grow much faster, larger, and more colorful than their indoor counterparts. This certainly held true with my cardinals as they have grown large and beautiful over the last six months. 88 degree water temperatures had no adverse effect on them. They even exhibited some breeding behavior, but my relative failure with the "planted" part of the aquarium certainly doomed any breeding effort. I should mention that I had a real worry that outdoor predators would move into the tank and eat my fish, especially since I have a waterfront property on a cypress bayou. However, birds, dragonfly larvae, waterbeetles, parasites, and other pests were not a problem. I did see the smaller species of water beetle in the tank one time, but I believe only because the light attracted it in at night.
The tank is situated in a corner up against the house so it receives no direct sunlight. It is lit for 14 hours a day with a single rectangular 400W metal halide fixture with a horizontal bulb, and therefore has extremely high light levels in the middle of tank and more moderate light levels on the ends. The light is situated approximately 2' above the tank, as this was the lowest setting that illuminated the entire top of the tank with the given reflector design. The lighting setup is nice because it leaves the top of the tank uncovered and exposed to the outside air.
The substrate is comprised of 2-5mm pea gravel from the local bulk-sale rock yard, which I slaved to wash thoroughly and to disinfect via boiling. It is a little over 3" deep in the front of the tank and 5" deep in the back. I added a thin layer of Seachem Flourite substrate in the middle, using four 15lb bags. I probably would have used more, but this was the entire supply I could find locally.
CO2 is provided via a 20 lb tank and a pH controller set to 6.75. I use reconstituted RO water with a kH set to 4dH using potassium bicarbonate. The GH is also set to about 4dH with Seachem's Equilibrium product. I keep a plastic garbage can filled with RO water right next to the aquarium for easy top-offs and water changes. Filtration is provided by a Fluval 304 canister filter loaded with the standard foam pads and three trays filled with sintered ceramic biomedia.
I used the fishless ammonia cycle to get the nitrification process going in the tank before adding fish and plants (I probably should have added some hardier plants from day one). This worked well for me, but took alot of time given I did not have a bacteria "seeding" source that I trusted to use in the tank. The process took 4 full weeks, but established such a good bacteria colony that when I introduced the fish (40 small cardinal tetras), that no ammonia or nitrite spike was observed.
I have had several planted aquariums over the years and probably my most successful was one of my first. It was a 45 gallon tank with three cheap fluorescent "plant and aquarium" bulbs over the tank and yeast-provided CO2. I must admit that as I have become more knowledgeable and high-tech with my tanks over the years (more light, reconstituted RO water, etc), I have had far less success getting plants to thrive and in keeping algae suppressed.
Instead of learning from this I did what many-a hardened advanced planted aquarium hobbyist would do-- attempted to fix the problem with more technology. This time, I conspired to beat algae from the onset by darkening the tank during the fishless cycle period and employing an extremely oversized (for the tank) 25 watt UV sterilizer thereafter to keep the algae spores from getting a foothold in the tank. Unfortunately, this only delayed the imminent algae take-over of the tank. I went cheap on the clarifier, and did not get one with a built-in wiper for the quartz sleeve. Furthermore, the way I plumbed it in did not allow for easy removal and cleaning. So, I have had it installed and uncleaned now for 6 months. I am uncertain if regular cleaning would have led to better success, but somehow I think not.
I bought some plants about two weeks after the fish and UV Sterilizer had been added. This was a novice mistake of which I knew better, but I simply procrastinated. That 400W light was burning down on the tank full of fish and devoid of plants, just begging algae to move in. The plants I bought include two swords, 6 crypts, some rotala, and several bunches of Glossostigma. Now I know the Glossostigma and some of the others were just a stupid decision for a new tank setup. In the past, I would have just purchased a ton of Hygrophilia polysperma to compete with the algae aggressively until the tank aged a bit, gradually adding more demanding plants later. But as many of you probably know, this plant has been listed a noxious weed by the federal government and is only available if you know a fellow hobbyist who still grows it. I used a 20-minute soak in a fairly strong solution of potassium permanganate to disinfect the plants, but this did not keep ramshorn snails from moving in with the plants. I'm not sure how well it disinfected the algae. Surprisingly, most of the plants "took" and started growing, except for the rotala, which melted away. Even the glossostigma started spreading horizontally along the bottom of the tank.
Still the growth was not even close to as phenomenal as what I had experienced with some of my previous tanks. Yes, I had been a little less aggressive with the CO2, given my plans for discus in the future. Occasionally I let the kH slip to 1 or 2 dH gradually over several water changes. Since the pH was kept constant by the controller, this meant less CO2 was available to the plants.
Eventually the plants started developing symptoms of moderately severe nutrient deficiency, despite me adding iron, potassium, and trace minerals regularly with water changes. My best guess is that the biological filter, (with its three trays of bio-media) is effectively out-competing the plants for ammonia. Certainly the high summer water temperatures contributed to the plant decline as well. Various forms of green algae started showing up gradually on the sides of the tank and on the leaves of the plants. The nutrient deficiency caused all but the swords and crypts to gradually fade away. The swords are nutrient deficient to this day. They exhibit smaller, yellower leaves, not the clear leaves you see with iron defficiency. The crypts are actually in fairly good health, however, and are spreading very slowly.
When tank temperatures rose into the mid-eighties during the summer, my second polishing filter (a magnum hot canister) gave up the ghost. Gradually the green algae was replaced by cyanobacteria (blue-green algae). Eventually the blue green algae took over everything in the tank, and to this day it recarpets everthing in a matter of one week after I siphon the tank, clean the plant leaves, and scrape the glass. This despite the fact that the water temperature has receded to the 80F heater setpoint. This does not seem to affect the crypts adversely as long as I clean off the leaves at least once every two weeks, but of course is really unsightly. I think the increased water temperatures, the decreased tank circulation, and the decreased water hardness all contributed to the blue-green algae taking over the tank.
Now that fall has arrived, I plan on forming an assault on the cyanobacteria and take back over the tank without resorting to antibiotics. I have already started raising the kH back up to 4dH to increase the CO2 levels in the water. I am also considering replacing the polishing filter to add back the additional circulation that was lost in early summer. I need to figure out the source of the nutrient deficiency for the plants, and am considering removing some of the biomedia from the filter.
Finally, I am in need of some Hygrophilia polysperma. Would any of you be willing to contribute a few stems to the battle? I will gladly pay for the value of the plants and the shipping! If I do add discus next summer, what plants do you recommend keeping in a tank that has 82 to 88F water temperatures? Is my only option to buy mature discus and a chiller to keep temps at 80F? Do you have any personal stories of success with plants at high temperatures? If so, I would love to hear them.
I would have added a picture of the setup to this post, but my wife is out of town this weekend with the camera.