I have the Oase Pondovac5. I love this vacuum. I rented the PondoVac4 for a day to try it out and then invested in the Pondovac5. The continuous use is a godsend for me. My pond is completely surrounded by trees: oaks, southern magnolia, cedars, tulip poplars, walnuts, southern catalpas, red buds, weeping willow, American elm, silver maples, dawn redwood. You catch my drift that I have nonstop tree mess to clean up. I do t have anymore of skimmer, well not true - I am the skimmer

! This year we have had a tremendous amount of severe weather making it an even harder job to keep up with the debris. My stream is 100feet and all 100 feet covered by trees dropping their stuff along the way.
I use the vacuum a lot in spring and fall. Summer and winter feel like a much welcome pond work break. If you have a bog, it is very helpful for cleaning the bog as well. There is an attachment that will limit gravel being picked up, but what does get picked up I just catch in the netted bag (it comes with), gently rinse of the rocks with pond water that I vacuum out and then return them to the bog.
My pond is odd shaped and build into the side of a hill where the waterfall lies. This vacuum has enough tubing that I can reach anywhere I need to vacuum from the pond edges. I haven’t had to order any replacement parts yet, but it seems easy to do should the need arise from their website. Take good care of the vacuum and clean it well after every use. It definitely is a heavy vacuum, but this model does come with larger wheels than the other model which helps to maneuver it around your pond.
Now, I don’t know anything about your pond, but for me it is a must have. The cedar tree that hangs over my pond drops tons of needles that I could never scoop it all. My pond is mature and an efficient beautiful bog filter, which was built around 2000, and I took ownership in 2020, but it requires some help to keep up with the debris. If you don’t have tons of trees, then maybe you won’t need one. I have a pair of waders and long gloves and I don’t mind climbing in regularly to clean up the bottom - so perhaps that’s an option for you instead depending upon your landscape.
If you have any questions about the vacuum, just hit me up. I am happy to answer.
