Re-starting nitrogen cycle

[Muckman]

Hi again, sorry, I laid this whole long message out in the Introduction forum.
Here it is again in the (?proper) place.
Thanks again in advance for any comments!
Muckman
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I inherited responsibility, years ago, for a public goldfish pond near my house. Approx 1500 gallons. The pond is shallow (about 1 foot deep overall), but with 2ft X 2ft refuge/planting holes, below the concrete bottom, in four places. It has never been stagnant, as (I assume) the breeze keeps the shallow water moving enough for oxygen exchange, & the balance of a few fish & a few plants was working fine.

After many years of being satisfied (but not thrilled) with the same old hardy water lilies, and being somewhat worried by deepening sediment & a spotted 'fungal' problem with the plants, I arranged for some volunteers to help me get most of the sediment out (assuming that was where the fungal problem came from). Of course, while I supervised pumping the sediment out to the surrounding flower beds (150ft away or so), some vigorous scrubbing was going on & large areas of the pond bottom (concrete) were stripped of bio-film. Two large areas of the pond were NOT scrubbed, & I hoped that those would help restart the nitrogen cycle after the pond was re-filled with water. There is no electricity available for a permanent filtration system (historic house & grounds plus no budget for equipment/installation). Never had it, never gonna get it.
Now, six weeks later, (starting with half city water & half rainfall to fill the pond) with some new plants added, & one old-growth original water lily still in there, undisturbed, the water slowly turned a creamy, tan-colored opacity, & now has a definite dark-green coloration. This was my worst fear, that a huge algae bloom would take over, & so I was dosing the pond with nitri-fix bacteria, (~ 6oz per week) as well as dropping in as many other (temporary/bare root) plants as I could, to try & take up nitrogen. Regular Ammonia/Nitrite/Nitrate drop tests all show ZERO nitrates in the pond(!?) I've even ordered new testing reagents, just to make sure I'm correct on this. I have barley straw ready to suspend in there, & even more bare-root plants available for emergency nitrogen mop-up, but I would really appreciate any thoughtful comments on what's going on, & what more I can do to get this little body of water back to the good-old-days when it was clear & healthy, due to near-total neglect!! How can there be green color without nitrogen? How long until the green stuff dies, gets converted by the good bacteria (into good old sediment!), & the water looks clear again?? Do I just need to be patient, or is there something I haven't realized that I can correct for?
I thought I knew enough to keep all this from happening, (& everyone around thinks everything's just lovely, because (most of) the plants have been blooming normally!). There were very few fish in this pond after last season (blue heron), but the surviving two dozen 4" replacement goldfish looked healthy in the weeks after cleaning (until the cloudy water started closing in, so now I can't see them). Same for the Gambusia, who have prospered since before my time, & still cruise around in there like nothing happened. I have notes & photos of our history with re-potting plants, etc, but to keep this short on introduction I'll just post it & see if anyone wants to comment.
Thanks in advance here . . . ..... Muckman, Astoria, Oregon.

 

[JRS]

Welcome to the forum.

At this point I would just be patient as you mentioned and give everything some more time to stabilize. The algae is helping suck up the nutrients as well as the plants which is why you have zero on your nitrogen cycle readings. If everything goes right, the green water algae will eventually crash and the pond will clear. Are you feeding all those fish? If so, that will delay your desired result.

 

[Muckman]

Welcome to the forum.

At this point I would just be patient as you mentioned and give everything some more time to stabilize. The algae is helping suck up the nutrients as well as the plants which is why you have zero on your nitrogen cycle readings. If everything goes right, the green water algae will eventually crash and the pond will clear. Are you feeding all those fish? If so, that will delay your desired result.

No, no one is feeding the fish, although I thought about putting in something to jump start the cycle. Over the 8+ years that I have paid attention to this pond we have mostly relied on any algae & whatever else the pond water provides to keep the fish fed. Mosquito larvae, & things like copepods, blood worms, & plant material. No commercial fish food. The number & size of the current fish population seems quite small for the volume of the pond (approx 24 small goldfish + the little Gambusia minnows, for 1500-2000 gallons of volume). I had assumed that the present nitrogen load from fish waste might not be enough to register on the tests, at least not immediately after cleaning. The fact that the pond was scoured pretty clean, AND the new plants were all starting fresh (clean roots, clean potting medium, with hardly any source of nitrogen in the pots), made me think that the N2 cycle had been delayed in starting for lack of a source of ammonia/nitrites. No source of decomposition, with leaves & sediment all cleaned out. The only actual food for plants in there is in the form of time-release fertilizer stakes buried in the water lily pots; mostly phosphate (for flowering), & much less nitrogen/potassium. I use a fairly inert soil mix of local clay & sandy loam, with extra minerals from a sprinkling of lava rock (iron), crushed oyster shell (calcium), & Epsom salts (magnesium & sulfate). And I did add pond salt after the cleaning.
Thanks for responding here! Yes, at this point I'm just making myself be patient & keeping debris off the surface. Doing water tests & adding small doses of nitrifying bacteria. The recent heat wave with bright sun really boosted the green water, so I go over almost every day & try to make it clear up by staring at the pond & concentrating real hard!

 

[Mmathis]

First of all, I want to applaud you for thinking about cycling the pond. So many people are totally ignorant about the importance of the nitrogen cycle, and the consequences of not doing so.

Do you have a water test kit? Is that how you are monitoring the cycling?

Continue with PATIENCE, and don’t add anything to the pond. Mother Nature can’t do her job adequately if we interfere.

 

[Muckman]

(from first post: "Regular Ammonia/Nitrite/Nitrate drop tests all show ZERO nitrates in the pond(!?)"

Yes, I've been using API dropper-style liquid reagents, with an expiration date of 2025, as mentioned above. I also had a test kit specifically for GH & KH that is now outdated & a new kit just arrived last night. (Will test the pond with it later this afternoon). I have also been using some paper test strips to try to confirm the dropper tests, & they mostly do confirm the results. I find the test strips a bit hazy on what exactly the color is supposed to be (it fades & changes rapidly as the strip dries out), so I'm mostly relying on the drops.
As for 'not putting anything into the pond', I have NOT added any ammonia-generating stuff (like extra fish food or whatever), since it seems there is enough nitrogen in there that the emergent plants & water lilies haven't turned yellow. But I am still putting a (tiny) amount of nitrifying bacteria ("Nite-Out II Pond Microbe-Lift Nitrifying Bacteria" from Ecological Laboratories), using directions on the jug (5oz per week = less than a cup, for 1500-2000 gallons of pond volume), just to re-enforce whatever other nitrifying elements are at work in there.
Also, I (& others who work at the gardens) have to top up the pond (extra warm & windy here lately) with city (slightly chlorinated) water from a garden hose, so one more rationale for boosting the good bacteria is in case the chlorine is wiping out a portion of what's there already. We have used city water for years in this pond without perceptible harm to fish/plants/ecology . . . .... we just add it in small amounts at a time, to keep the volume topped up.

Mostly I've been sinking lots of extra water lily tubers into the pond (no pots, just bare roots, weighted to the bottom, to encourage upward growth in leaves) to act as a temporary 'sponge' for nitrates when they DO start showing up. That is so any nitrates that the official plants can't handle don't go toward making more green water or other algae. When the pond clears & all plants are growing bigger I can easily snag these helper plants out to leave some open space for people to see the fish.
When I re-pot water lilies (every 3-5 years or so), I end up with lots of healthy tuber chunks left over & I tend to toss them into tubs & barrels at my house, along with other survivor/propagation experiments, so I always have extra plants looking for room to grow!

 

[Muckman]

Update on this thread.
After fretting about this pond since June, the water is finally starting to clear up. I did suspend some barley bales in two of the planting holes, & kept dosing with the nitrifix bacteria. One early good sign was when I started catching scads of tiny Gambusia fry in the skimmer net (hand net w long handle, like for swimming pools). That meant they were happy in there, despite the cloudy water. The water lilies have been blooming steadily, with very little sign of the fungus, & the irises & water mint are all spreading nicely. I still can't see the bottom of the pond, but am thinking that with the cooler/cloudier weather, & all the plants growing, that the risk of more major algae blooming has dropped.
Thanks to everyone who answered my posts!
MM