API POND-ZYME SLUDGE DESTROYER (8 oz) Pond Cleaner with Natural Pond Bacteria - Up to 8,000 Gallons - Reduces Fish Waste Buildup - Consumes Muck & Sludge - Spring Start Up & Regular Care

Best I’ve found to kill string algae and control my pond. Water stays clear. Red eared slider is happy. Fish are thriving. Totally worth it and I’ll be using this forever.

I buy this yearly and it turns the leaves at the bottom of the pond into sludge and gets removed by my filter. Very easy to use!

Initial week’s dose seems to be having some effect on the clarity of the pond, will continue on with the next dose next week. Hard to figure out dosage for the volume of water in the pond, UPDATE, several weeks have gone by and 3 doses put in so far, it is most definitely working and making a difference in the pond.

I use this and the algae fix and between the two I have noticed a huge improvement. This more than the algaecide definitely. I’ve had the pond 10 years and this is the first year the algae is actually slowly coming off the sides and bottom. It’s literally a 7 x 15’ concrete hole in the ground next to the front door with a waterfall and fountain. It’s gorgeous and I put a lot of effort into keeping up with the algae. I have probably 100 fish in there so between uneaten food and waste.. the algae and buildup around the ornaments is just nuts. I mean I could probably get away with less upkeep, but I enjoy interacting with the bigger cichlids and it’s a nice quiet time for me. The ornaments always get caked with algae no matter what. And the rocks and waterfall, too. This doesn’t really help that thick black algae that builds up on the rocks. API makes a waterfall oxi powder but i’m too scared to use it bc i’ve seen reviews saying all their fish died. I may get it and use it on smaller rocks outside of the pond but not in it. Anyway this mainly just keeps the floor and side walls clean. Water too obviously but knock on wood the water has been consistently clean for quite a few years. I’m pretty much just referring to the constant fish waste and algae buildup around the ornaments and in general. I’ve noticed im starting to actually see the cement instead of one thick green blanket up to the water line. The plecos are starting to eat more fish food bc of the significantly lower algae count. Overall i’ve noticed a huge reduction in algae since adding this to my pond maintenance schedule. It’s June now so i’m sprinkling a little bit in every other day and algaefix every 3 days. I’m in Florida and this will probably go on till October when the heat and sun let up a bit. But this is huge volume and the first tub lasted almost a whole year of constant use. Good stuff.

My pond was getting a lot of algae and so I wanted to clear it up. I added the amount the instructions said. 2-3 weeks later it basically turned it in a large pond of gunk. There was thick algae gunk EVERY-WHERE! EVERYWHERE! Caked all over the filter top too. AWE! I can't believe my fish could breath. I could barely see them through it. I ended up removing the fish and draining 95% of the pond, scrubbing and starting over. I am sure that the plants that I put the water on will do great though. Maybe I did something wrong IDK. I only added it once. Maybe I was suppose to do more. I can say that when I drained the pond, there wasn't much black stuff at the bottom as I had expected.

Combined with Accuclear -works great.

I am amazed by this product. I have tried many kinds of products for control of algae and muck. All others were either ineffective or they were expensive short term fixes which created other problems by their use. After a while I had pretty much sworn off using any of these commercial preparations. I have a biofilter and UV light but I live in Southern California where my pond is in sunlight all day long. Water temps in the summer are in the low 80's and that's a recipe for algae growth. When I started using API Pondcare Pond-Zyme I realized this product is different. It really does help to keep the algae and muck in control. I now use two to four scoops per week for my 4,500 gallon pond. I can clearly see the bottom (5-1/2 feet) and have minimal problems with algae and muck. If I forget to add Pond-Zyme I will notice string algae beginning to grow and that reminds me to add it again. I notice results within 48 hours and the benefits seem to last a couple weeks. When I stay in the habit of adding a scoop or two twice a week the pond stays nice and clear. Update: Two years later I am still using this product and am very happy with the results. For maintenance, I don't worry about the dosage instructions on the label. I just add two scoops to my waterfall or skimmer every few days. That way I don't have to remember when two weeks have passed. My 4,500 gallon pond stays clear right to the bottom - even in hot weather with a fish load.

I don't usually write reviews, but this company has been unresponsive to my requests. Here's the situation: I clean out my small backyard pond once a year. I have to wade in and pull up about 1" of muck and growth. When finished, the water is completely black. I let it settle and after about a week it gets clearer. This time there was a cloudy green opaqueness so I thought I would try out the API product. I used as directed and nothing happened. Each week I would add more product and the pond was not getting clear. After about 1 month of treatment, I sent a message on their website wanting to know what to do. That was going on a month ago. I then called twice and left a message each time. The calls were a week apart and I have still not received a call back. In the meantime, the pond has cleared up a bit and I wanted to know if I should be using any other product to assist in cleaning up the pond. I have been getting some algae as well. So I can't verify the product efficacy but I can provide an opinion on their lack of customer service. I will not purchase anything from this company based on the lack of service. Amazon directs you directly to API so there is no help with them.

Very happy with this exceptionally easy to use product. Very happy that pond is starting to look better

I have a small outdoor pond with frogs living in there. The water was dirty and smelly. I tried a few natural things without chemicals but nothing worked until I used this. Now after a couple of weeks I can see the bottom of the pond and the smell has gone.

A little goes a long way. We add it and by the third say the water is crystal clear. We've used it a few time overthe year and it's amazing

Very good, did on excellent job on my swimming pool converted to koi pond ( still 5' deep) very happy with this product

This product just did not deliver what it promised i.e. a clean pond. It is totally ineffective and waste of money. All claims made for the product are false. Extremely unhappy and feel cheated of my money. Would never buy it ever again.