New RTC pond.

[gdc7688]

Thanks again Viktor and Scleropages for the great advice. Decided not to get TNS as i plan to rear fancy guppies with my RTC's. I realized that they are too lazy to hunt for small fishes and the guppies just breed too fast for them to be wiped out.

My old ponds had about 2500 gallons combined. My new RTC pond is about 1700 gallons and 2800 gallons combined with the filters. I have given away all my other fish except for the koi and RTC's as I've learned the importance of not overstocking a pond.
I've also taken a recent interest in rearing jumbo kois. The new koi pond will hold 6000-8000 gallons. Plan is to allocate 1000 gallons per koi. Hacking of the front pond is completed and the RTC pond is scheduled to be completed by today.

2 pumps in the RTC pond will turnover 30,000 litres of water per hour combined. The waterfall box seen in the picture will be planted with a tropical palm that is excellent in absorbing nitrates. However, the pond will be acid washed and left to run for about 3 weeks before i transfer the RTC's. They are now held in a 200 gallon holding tank and doing well.

[dw1305]

Hi all,

Is it really in full sun? I'd never thought you stand a chance to keep green algae (pea soup) from messing up the water clarity with just a veggie filter - plants do not take up enough nutrients and there is plenty still left in the return water for the algae to feed on.

I don't know where this idea came from, plants are an order of magnitude more efficient at water treatment than microbes, and combined microbial/planted filters are being more and more widely used in waste water treatment and aquaculture.

The potential of the system is dependent upon the availability of light energy (PAR - photosynthetically available radiation), and more light = more potential for filtration.

The other advantage is that you aren't left with high levels of NO3 (from the NH3- NO2- NO3 conversion), because the plants in the filter will remove it, and the whole system can remain aerobic, (because the anaerobic decoupling of fixed nitrogen and out-gassing as N2 isn't required). The advantage of this is that aerobic systems are much more robust and easy to manage. Extensive systems often use floating plants, mainly because ponds are cheap to construct and floating plants easy to harvest, but rooted plants like Reeds (Phragmites) or Cat's tail (Typha) in "constructed wetlands" are potentially even better.

This is the abstract of a paper where they give some figures for the levels that plants can clean the water up to. For those who aren't familiar with the units, totally unpolluted streams would have a BOD of less 1-2 mg/L and "clean" fresh water less than 5 mg/L BOD:
Zimmels, Y; Kirzhner, F & Malkovskaja, A (2007)
Advanced Extraction and Lower Bounds for Removal of Pollutants from Wastewater by Water Plants
Water Environment Research 79:3, pp. 287-296

The capacity to reach lower bounds for extraction of pollutants from wastewater by four floating aquatic macrophytes—water hyacinth ( Eichhornia crassipes), water lettuce ( Pistia stratiotes), salvinia ( Salvinia rotundifolia), and water primroses ( Ludvigia palustris)—is investigated. It is shown that the following lower bounds can be established for wastewater purification with water hyacinth: biochemical oxygen demand (BOD), 1.3 mg/L; chemical oxygen demand (COD), 11.3 mg/L; total suspended solids (TSS), 0.5 mg/L; turbidity, 0.7 NTU; ammonia, 0.2 mg/L; and phosphorus, 1.4 mg/L. Also, the following lower bounds can be established for wastewater purification with water lettuce: BOD, 1.8 mg/L; COD, 12.5 mg/L; TSS, 0.5 mg/L; turbidity, 0.9 NTU; ammonia, 0.2 mg/L; and phosphorus, 1.6 mg/L. These lower bounds were reached in 11- to 17-day experiments that were performed on diluted wastewater with reduced initial contents of the tested water quality indicators. As expected, water hyacinth exhibited the highest rates and levels of pollutant removal, thereby producing the best lower bounds of the water quality indicators. Given the initially low levels, BOD was further reduced by 86.3%, COD by 66.6%, ammonia by 97.8%, and phosphorus by 65.0% after 11 days of a batch experiment. The capacity of water plants to purify dilute wastewater streams opens new options for their application in the water treatment industry.

cheers Darrel

[Bas Pels]

Currently I am in the starting up phase of a set of pond like tanks (glass tanks, put on the floor, so mostly one looks down on them), in a veranda (it is open now, but will be closed again in winter). I intend to have a lot of cyprus growing out of the tanks, in order to remouve nitrates without me adding light to the tanks. I think this is basically the same system.

[Viktor Jarikov]

Excellent ed, Darrel. Thanks as always.

I don't know where this idea came from,

From the abyss of ignorance in my head I think I just never had enough plants in my koi pond for them to outcompete the microscopic green algae, unless 80%-90% of the pond was covered with water hyacinths.

[dw1305]

Hi all,

I think I just never had enough plants in my koi pond for them to outcompete the microscopic green algae, unless 80%-90% of the pond was covered with water hyacinths.

Yes, I think that is the sort of coverage you would need with fish and plants in the same pond. To keep this level of cover (and 10% - 20% open water), you would need to thin the Water Hyacinths every day. Additionally if the fish eat any of the filter plants that nitrogen remains in the system.

I think your conclusion (below) is 100% correct:

the only clear conclusion for me is that your filter cleans the water of minerals just superbly because you have warmth, you have sun light, and you have clear water => hence, the return water is close to RO water when it comes to major algae nutrients

With a system like the OP has, the recycled, filtered water should be low nutrient, and the ammonia production from the fish will be exported fairly rapidly into the planted trickle filter. This should make the pond less nutrient rich, and will dilute the green water problem (the planktonic green algae will still be there, but at much lower densities).

cheers Darrel

[gdc7688]

guys, sorry for going off topic but what kind of food should i feed my RTC's? they have been surviving on koi pellets and feeder goldfish the past few years. I would like to vary their diet as much as possible. Thank you.

[Viktor Jarikov]

I don't think your q is OTT. Rather vise versa.

You removed your OP vid?

RTC like anything fleshy - lean fish, shrimp, crab, mussel, seafood, etc. Pellets, any kind but not too fatty like for cold-water fish, are very good. Goldfish is no good - parasites+bacteria risk and too much fat. In the wild they eat fallen fruit too. To kill parasites, it is sufficient to freeze their food.

Flesh provides protein. Pellets provide vitamins and minerals. It usually suffices.

[gdc7688]

Thx again Viktor for the good advice . Video was removed as I deleted my old YouTube account . Something strange happened today. One of my koi disappeared in the holding tank . Let's just say I found where it was when I released the rtcs in the new pond .. A disfigured carcass of what resembles a fish was regurgitated shortly after . I took a pic but it's definitely not suitable for public viewing Btw, the new pond was chemically treated and rtcs promptly transferred as the holding tank was getting overcrowded .

[Viktor Jarikov]

I am not surprised at all if the following assumption from the foregoing can be constructed and is true: you held two 1 meter RTCs with some koi that could fit in their mouth in a 200 gal temporary holding tank. You'd be surprised how big that mouth and throat are. They are made to swallow huge prey etc. in the wild. I am sure 1 meter RTC can swallow a 1.5-foot koi, and maybe even a 2' koi.

The rule-of-thumb states tankmates must be at least 1/2 the length of a predator like the large Pimelodidae, assuming the similar body proportions/girth. When the predators get to be this big, I personally would go for a maximum safety margin - similar size. This does not pertain to skinny fish, e.g., a 3' silver aro can be easily part-swallowed by a 3' RTC and digested bit-by-bit (it's a bit too long even for the humongous stretchable RTC stomach).

Having eaten recently (within a day or sometimes even two) and having been subjected to a strong stress, as occurs during re-homing, my RTCs and many others did regurgitate often as well. Sometimes it even happens during my vacuuming a tank or making a big, like 80%-90% water change, so I don't feed heavily the day or two before or not at all.

[gdc7688]

Have been busy. Finally caught a little time for some updates.
My new pond is officially up and running except for the filtration part of it.
My Rtc's are doing just fine and have been feeding them a more varied diet following the suggestions of Viktor. special thanks!

My Filtration system will consist of a vege filter (as seen in the picture of my first post), and a 6 chamber mechanical/ bio filter.

The vege filter will consist of 4 pots of umbrella palm and 2 pots of thalia dealbata. Both are excellent in absorbing ammonia and nitrates according to the research I've made.
As for the filter chamber,
Chamber 1: settlement chamber
chamber 2: jap brushes for mechanical filtration
chamber 3 & 4: jap mat (bottom) and kaldnes K3 media on top with aeration by 70ltr air pump
chamber 5: ph buffer media (oyster shell etc)
chamber 6: UV, pumps *combined 30,000 litres per hour / pond size 1700 us gallons

[Scleropages]

Wow! That sounds like a great setup. Please share pics when it's all done.