Pond Boss Forums INTRO Questions & Observations Lanthanum based flocculate agents

Has anyone tried the Lanthanum based flocculate agents used in swimming pool applications for a pond application. It's used quite a bit to prevent algae blooms in swimming pools by tying up the free phosphate in the water column. It can be purchased in very concentrated containers, and it seems to me would work in a pond application to also prevent algae blooms. It suppose to stay in solution until it ties up with a phosphate molecule and precepitates out.

I have no idea what it would do to the fish or the rest of the aqua culture, but its safe for people in swimming pools.

If it ties up the phosphates what would happen to the plankton bloom? If there would be none then you would lose the base of the food chain. Might have a great swimming pond with some turtles , frogs and snakes and a bunch of starving fish.

http://www.eoh2o.com/files/Lanthanum_Toxicity-Discussion.pdf

ORTHOPHOSPHATE (PO4

3) REMOVAL USING LANTHANUM CHLORIDE HEPTAHYDRATE (LaCl2 .

7H2O)

Lanthanum chloride heptahydrate has been used for many years by various private and commercial institutions here in the United States and abroad, to remove high levels of orthophosphates from fresh and brackish water systems (Disney World and Sea World of Orlando, Florida – information provided by request only), as well as the recreational pool and spa industry for over 20 years. Industry wide application rates have been denoted that lanthanum bonds to orthophosphate at a ratio of 1:1. Simply stated, it takes 1ppm lanthanum to remove 1ppm orthophosphate from water. As dry weight, this equates to 16 pounds of 35% lanthanum chloride heptahydrate to remove 1ppm orthophosphate (PO43)
from 1-acre foot of water. This ionic attraction takes place within several seconds of contact of the lanthanum and the orthophosphate in both the water column and/or sediment. Lanthanum retains ionic bonding at pH levels between 5 and 11,
making it highly useable in most water systems for orthophosphate reduction. The lanthanum acts as a flocculent, capturing the orthophosphate and settling to the lake or stream floor, or in recirculating system, being trapped for removal by mechanical filtration. Once bonded, it removes the orthophosphate from utilization by both microbial and algal species. Unless exposed to highly acidic or alkaline waters, the ionic bond will not release. As lanthanum has an ionic bonding level comparable to sodium, lanthanum will also bond and flocculate carbonate (CO3), arsenic, selenium, and chromium. Application rates can vary due to the presence of these other minerals.

Lanthanum is widely used in Japan to remove both arsenic V and arsenic X from freshwater drinking supplies (Water Environment Research, Vol. 71, pp. 299-306,1999. S. Tokunaga, S. Yokoyama, and S.A. Wasay) meeting the Japanese Effluent and Drinking Water Standards, by treating at a 3:1 ratio of lanthanum to arsenic. Again, flocculating the arsenic for removal by rapid filtration.

My thinking is to not saturate a pond to bring Phosphates down to zero, but to get the levels sufficiently low to prevent ugly algae blooms and floating mats. I'm assuming algae is further up the food chain, so plankton would survive but algae would not have enough phosphates present to grow out of control.

I'm trying to find other means to control my algae than the constant Cutrine treatments.

How big is your pond country boy?

Could you take one litre of your pond water and add the Lantanum incrementally?

You could evaluate on a g/L or ppm basis so you could make a conservative application.

I'd recommend investing in a pH test kit so you could evaluate pH variations with each gram added.

I'd like to hear your results.

so, as water goes lake to lake down the watershed the water passes thru a holding pond to which the Lanthanum chloride heptahydrate is added and just need to know upstream phosphate ppm and flow rate. then floc would settle in holding pond then floc could be removed, ph has to be way out to not work, what does that stuff cost?

I will take everyone’s recommendation and run an experiment this weekend. I have all the test kits, PH, hardness, phosphate, etc. I also have the Lanthanum Chloride. I will check the pond water before adding the flocculate agent, then slowly add to say one liter a drop at a time. I will add until the phosphate levels get under 0.1 ppm. I understand that's the magic number where algae growth should substantially slow down. I will also check PH and hardness.

From this I can extrapolate the amount needed to treat the whole pond. I have one surface acre approximately 6-7 average depth. I can then determine the cost benefit trade off.

One concern I have based on the above post is the Lanthanum will also flocculate with carbonate. I know I have hard water, so the carbonate may consume all the Lanthanum Chloride before it has a chance to tie up with the phosphate. This would require way too much to be cost effective.

I'll let the forum know.

Country Boy :

An off the wall idea for thought. Most FA forms on the pond bottom and only floats to the top when it has produced enough gas ( not sure if O2 or CO2)which gets trapped then it floats up on its own . If you take the phosphate out of the bottom half of the pond water by pumping Lanthanum Chloride in solution through a hose to 3 ft. deep you may be able to kill the FA base but not the plankton on top. You also may be able to reduce the amount as you will only be treating 1/2 the pond. If your pond has FA all over the surface this may not do well for you.