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What is the scoop on Red Algae in Ponds

Posts: 74
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So in January my pond was mostly swallowed by a sink hole.  We fixed it in March $$.  Then the spring rains were sparse, so it is now about 1/2 the area (if that) and about 4 feet shallower (The dep point was only about 8 feet)  We have had some July rains that brought it up a few inches, but now we have red algae.
So in January my pond was mostly swallowed by a sink hole.  We fixed it in March $$.  Then the spring rains were sparse, so it is now about 1/2 the area (if that) and about 4 feet shallower (The dep point was only about 8 feet)  We have had some July rains that brought it up a few inches, but now we have red algae.
1.  The Red algae does not build up all that fast unless the daytime air temperature reaches about 88F (31 C)  Then it rapidly covers the pond.  
2.  I put a pump in the pond that shoots up a 12-18 inch geyser and it does very little good during the day but if I run it all night the pond is clear by morning.
3.  Once the air temperature is in the mid 90's F (35C) the algae suddenly turns light Green  But reverts when the temperature goes back down.

4.  When the red algae is covering much of the pond the surface water feels like warm bath water.
5.  After running the pump all night and the water has cleared the pond surface water feels mildly cool
6.  If the wind is blowing across the pond as a steady breeze maybe 10 mph (16Km/Hr) the algae does not form even in temperatures in the warmer temperatures and the pond stays at least mostly clear.

I am surmizing that
a.  There is a "trigger temperature" for the Algae formation and another higher one for the color transition.
b.  Since making the Geyser is effective at cooling the temperature at night but not so much during the day, that the coolness of the night air is as importantant as aereation and getting the pond surface below the "trigger temperature"
c.  I have never heard of algae suddenly changing color and am simply ignorant about that phenomenon

I would like to know more about this algae if any one can advise me, (e.g. is it really a problem and if so is there any thing to do that is more cost effective than running a 720 Watt pump all night?

I took some pictures to show the pond with Algae and the sort of Geyser I get from the pump but I cannot seem to post them even though I have posted pictures before, did the web site picture policy change in the last month or two???
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Hi Don.
from all that I've read, you'll need to increase the oxygen level in your pond and reduce the  level of nitrates. A call to your county extension office might yield some other ideas
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Location: Arkansas - Zone 7B/8A stoney, sandy loam soil pH 6.5
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When the red algae blooms in the oceans, it is called a "Red Tide", the red algae in ponds and lakes is the same organism, not a good critter at all.

Red algae eat up all the O2 that is dissolved in the water, which kills any fish that are living there. It also stinks all on it's own, never mind the dead fish contributions.

Oxygenation of the water is a good start, and as you mentioned, temperatures have a lot to do with blooming of red algae.
The easiest way to slow pond heating is to have trees growing near the edge of the pond, this will provide shade to the water which will help keep the temperature down some.
Current is another way to keep the temps down in ponds. Lakes already have current by virtue of their size and the fact that warmed water rises while cooler water sinks.
So when you set up a pond, taking into account the sun travel, providing areas that will be shaded either all day or at some time of day, will help set up a current in your pond which will have the effect of reducing the chance for a red algae bloom happening.

Don Goddard
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As to the oxygenation of the pond water and its beneficial effect on algae blooms.   I made a beneficial modification of my pump q44qnt3m3n5.   The pump came with a 1.25 inch (pipe size) threaded outlet.   It also came with a stupid cheap garden hose adapter for the outlet.  I call it stupid and cheap as this adapter simply gave an abrupt recuction in the outlet size which is known to result in a substantial flow loss.  

With this adapter in place the water would squirt straight up for a distance of about 18 to 24 inches and fall back in and around the bucket.  Leaving it off resulted in the water simply gushing a few inches above the outlet and even a whole lot less unless if the discharge opening was below the water surface.

To correct this situation I made some additional parts.as shown in the 1st image below.
I used 1.25 inch PVC pipe because I could get a fitting to screw onto the pump and there would be the least change in diameter of the flow through the attachment.   any changes in diameter tend to cause loss of flow and abrupt changes are the worst.   The new discharge has a 45 degree elbow on the end and that is not glued so that I can conveniently rotate the elbow, the slight taper inside the fittings makes for a good reliable friction fit as there is virtually no internal pressure in the pipe in such a free flow situation.   The key is that the internal diameter of the pipe actually measures 1.365 inches and the flow velocity varies by inversly to the cross sectional AREA of the pipe which means it varies inversly to the square of the diameter of the pipe   Accordingly I made the outlet of the aluminum nozzle 0.960 inches which gives me almost twice the velocity of the flow.  It is critically that the change in area be as gentle and gradual as possible .  I made the aluminum nozzle as long as the the elbow allowed and the inside tapers from the fitting diameter to the 0.960" dimension.  The second image shows how the pump and discharge are placed in a perforated 5 gallon bucket that serves as a trash screen.   The pump will readily pass what little the fine soft silt makes it into the bucket and the large diameter of the bucket makes sure that the flow rate into the bucket is slow enough to minimize how much silt actually reaches the pump.

Whth the angled discharge, the stream of water comes out in an arch that lands well outside the bucket in any direction desired.   I waded into the pond and drove a steel fence post so that the extension cord connection could be secured well above the water and the bucket could be attached to the post for stability.

With this apparatus the jet of water was much larger and impacted the pond surface with considerable horizontal velocity.   In about 15 minutes the jet of water had cleared a path through the algae about 6 to 10 feet wide and about 100 feet long.  In an hour or two the cleared area extended virtually to the opposite shore and had grown much wider.   Allowed to operate over night the pond was cleared of algae except for some secluded areas at the edge of the pond the pond surface would be algae free. and the pump can operates fro pennies a day.   If shut off the pond (1.8 acres at high water) wold remain clear until well into the afternoon.    My first concern was that in the hot summer afternoons the fish would not have enough oxygen and there had previously been a few fish going belly up.  With using the pump just intermittently there was no further problem.

As this small, 6amp 120 volt submersible pump (about 1 hp) had no problem runnng at the end of 200 feet of 14 gage extension cord run from a GFCI outlet on the house. As it is submersable there is no problem with the pump heating up,   I placed the bucket deep enough that the rim was about 3"inches above the water.

Hint:  If your pond has a soft bottom, and if it is safe, go barefoot.  That way your feet wont get stuck!
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Pump Components
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Pump Setup
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