Here is some info on the question of fertilization of ponds.
Fertilization of ponds is a tool to use in the proper circumstances only. Like a hammer can be the right tool to drive nails it is also not a good tool to cut tile or glass. I don't blame the hammer if I break the glass trying to cut it to size. It is nether good nor bad but a tool.
If you have a natural bloom and 18in visibility you probably don't need any fertilizer. Most ponds do not need a fertilizer program as they have natural fertility. If such a program is not needed then you will not need as much lime. It is still good to add lime if your alkalinity is low as it allows your natural fertility to work better and buffers the pond against big pH swings. The real key is the closer the pond water pH is to the pH of fish blood (average blood pH of 7.4 for fish) the better the fish thrive. Nature's simplicity at work.
Very important ""Waters that are low in alkalinity or total hardness (below 20 mg/L or ppm) will need liming in order for fertilizers to be effective."" Also if pondweeds or FA are present they will use the fertilizer instead of the algae that will be comprising the bloom.
Here is a link on the subject from SARC.
Fertilization of Fish Ponds see Fact Sheet 471 under Water Qualityhttps://agrilife.org/fisheries2/fil...-No.-471-Fertilization-of-Fish-Ponds.pdf
Other Good Topicshttps://fisheries.tamu.edu/aquaculture/water-quality/
The Other Side of Fertilization Especially Northern Ponds. Pros and Conshttps://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=559585#Post559585
Before a fertilizer program is started I think it wise to have the water and soil tested. Next it should be determined if you need such a program by watching visibility for at least part of the spring/summer after any non-fertilizer limiting factors are removed ( like low alkalinity below 20 ppm or serious turbidity). Often in low alkalinity situations fertilizer is not needed. Once the lime is added then a bloom will start on its own. That means fertility (N,P K) was not a limiting factor. While that is going on read all you can about the subject. Here is a list of times/situations where you should not fertilize. PLEASE READ THIS AS IT CONTAINS SEVERAL IMPORTANT POND MGT.CONCEPTS like do you really want a bunch more small fish to manage !!!!! From http://msucares.com/pubs/publications/p1428.pdf
page 16 starting :
When Not To Fertilize
Some ponds should not be fertilized. Here are some cases where this is true:
� Muddy ponds. Mud prevents sunlight from passing through the water. Plankton must have sunlight to grow. If a pond stays muddy most of the time, do not fertilize the pond until the mud problem is corrected.
� Ponds infested with trash fish. If undesirable fish dominate the pond, poison the pond, restock, and then begin fertilizing. Request Extension Publication 1954 for details on renovating farm ponds.
� Ponds infested with weeds. During warm months, pond weeds use up the fertilizer that the microscopic plants should get. Therefore, the pond stays clear even after repeated fertilizer applications.
� Ponds not fished heavily. Fertilizing a large pond is a waste of time and money if you fish it only occasionally. You just produce more fish that aren�t caught.
� Unbalanced fish population. If the bream population is overcrowded, it means there are not enough bass to keep the bream down. It would be foolish to fertilize if this condition exists. Request Extension Publication 1952 and Information Sheet 1479 for information on how to determine balance and to correct problem populations.
� Catfish ponds. It is not necessary to fertilize catfish ponds if a feeding program is followed. Where a commercial feeding program is not followed, fertilize in the same manner as for bream-bass ponds.
� Excessive water flow. In some spring-fed ponds, the volume of water flowing through the pond is too high to maintain adequate plankton blooms. In this case, fertilizer is constantly being diluted and will have little positive effect.
� Continue fertilization program from year to year. Discontinuing a fertilization program will leave you worse off than if you had never started one.� Improper fertilization, once or twice a year, is worse than no fertilization.
� If a bloom does not develop after four applications of fertilizer, check for lime requirements, excess water outflow, excessive weeds, or muddy water.
� Do not attempt to kill weeds by applying fertilizer.
This is one instance where I want everyone to please remember what Bill Cody tells us "It all Depends". Every and I mean every pond is different wrt this subject. Until one has experience with their pond and how it reacts to fertilizer (organic or inorganic) go slow. I mean real slow. Just dumping in a bunch of lime and fertilizer is a recipe for disaster. This is a tool to be used as needed and only in the proper situation and correctly.
If you find another good post on fertilization post it or send me a PM with the link.