[tmreeves99]

I have a greenhouse with passive solar heating. It is warmed by a 600 gallon 'pond' (absorbs heat during day...radiates back to greenhouse at night). The pond has a biological filter (bio-balls) with a small spillway. I have decided I now want to add some aquatic plants to the pond. I plan to keep several water lilies and lotus, and will select some type of floating plant to bring the surface coverage up to about 60%. I will not be adding fish to the pond.

The lilies will be planted in containers having solid sides and bottoms (not the open mesh 'basket' style) placed at an appropriate depth. I will feed the lilies with fertilizer tabs placed in the bottom of the containers.

MY QUESTION: Will enough fertilizer diffuse out of the lilies' containers to support the floating plants? I will NOT add fish. Thus far, the only advice I have seen regarding this question is to '...temporarily re-locate the floaters to a bucket with fertilizer, and then return to the pond.' If that is the only answer, I will abandon the floating plant idea for my pond. Thank you, in advance, for your advice.

 

[mistergreen]

The root tabs will be soaked up by the Lillies. The floating plants will have a hard time with no nutrients.

 

[Michael]

Healthy water lilies and lotus will easily give you 60% surface coverage, if not 100%.

 

[tmreeves99]

Thank you mistergreen and Michael. I admit to being an aquatic newbie here, and you provided some helpful info. I'm not quite ready to abandon the floating plants idea yet. Especially, I was hoping to hide my oversized biological filter. I was planning to confine some of the floaters to the reservoir part that holds the filter material (just upstream to the spillway).

So...I guess my question changes to "is there a way to add fertilizer to the entire pond, without an algae catastrophe?". Thanks again, Tom.

 

[mistergreen]

Do you have any animals since you have a filter? Turtles maybe?
Animal waste should provide some nutrients.
Yes, you can add nutrients. We planted tank people add small amounts of nutrients every day.

 

[tmreeves99]

I understand mistergreen's question is a fair one. I would want all the above fauna, including fish, if I had a nicely designed outdoor pond in, say, a garden setting. However, the greenhouse water tank (see attached photo) would be, in my opinion, a not-fun place for animals. Also, I really want to experiment, first, with a plant-only system. So...with all the confidence that a newbie can muster, I plan to look at the various fertilizer products that might be used in a whole-pond administration. (any advice on that would be welcome). When the algae takes over the greenhouse, I'll probably be back on this forum with more questions.

 

[mistergreen]

How well does the heat battery work?

 

[tmreeves99]

I actually just finished building this greenhouse, and have not been thru a winter yet. When the weather turns cold I will remove the white tarp I have on the 'pond.' The sides of the pond are painted flat black to absorb more heat. I'm in central Virginia (growing zone 7), so we have pretty mild winters (only a few days between 0-10 F). During the present heat wave it has been seriously hot in the greenhouse (100 + F), even with an exhaust fan. However, I am convinced that the heat battery also has a moderating effect on the heat by lowering the ambient temperature a few degrees. Sort of a buffer or capacitor to resist crazy temperature swings. The few plants my wife has placed in the growing beds seem to love the heat.

 

[mistergreen]

I'm in zone 6. I built a shed-size greenhouse to over-winter herbs and trees. I used a heater and insulated the inside with plastic for the winter.

 

[Michael]

Very interesting set up! Long ago I built a solar heated chicken coop using the same principle. The thermal storage was 5 gal black metal containers stacked inside a south-facing plexiglass exterior wall.

You may want some fish for a purely practical reason: mosquito control. Depending on water temperature gambusia or small goldfish would work. Or you could use BT wafers, a.k.a, mosquito dunks.

If the soil and fertilizer in the water lily pots isn't enough, you could use almost any type of terrestrial plant fertilizer that you already have. Start with very small doses and increase until you see the desired growth on the floaters. If you have a major algae bloom, do a big water change and reduce the dose of fertilizer.

Please let us know how it works.

 

[tmreeves99]

Appreciate the practical advice, Michael. The reading I've been doing, trying to get up to speed on aquatic plants, seems to focus on endless genus/species distinctions...without the basic DIY info that I need now.

Mosquitos: I was hoping the spillway filter would provide enough agitation of the water to discourage mosquitos. But that remains to be seen.

Fish: Yea, I'm starting to soften on my decision to remain fish-less. But I like to experiment with one variable at a time. So, I'm going with the start-small-and-increment approach to fertilizer. Animals later.

Chickens: Maybe I'll add chickens to the greenhouse (..just kidding).