The problem with your water is probably all the chemicals you keep dumping into it combined with your lack of patience, but may also be insufficient filtration. First tell us how big your pond is and also what you are using for filtration including your pump's flow rate. Do you have any other air flow in the pond such as an air pump with an airstone or a waterfall? Next, throw all that chemical nonsense into the trash and add PLANTS to your pond (but I might drain it and start over first, because many algae-killing treatments are harmful to plants). Plants should cover 2/3 of the surface of the water, ideally. Floating pond plants are your pond's best friend, but also have some submerged potted pond and marginal plants in planter baskets along the pond edges. The only water treatments you should ever be putting in your pond is one that neutralizes any chlorine when you add new tap water, and one that adds beneficial bacteria. If you are a fan of Cloverleaf brand products (or they are all that is sold in your area), here are the only two of their products you would use in your pond:
https://www.pond-planet.co.uk/pond-c1/pond-treatments-c23/cloverleaf-chlorine-answer-p64
https://www.pond-planet.co.uk/pond-c1/pond-treatments-c23/cloverleaf-absolute-bio-gel-p2812
I recommend, after dumping all those toxic chemicals in there, actually draining the pond one more time and starting totally over with new water again, but keep in mind, you will be starting over and you will have an algae bloom for a while before it clears up. That's called cycling, and it takes a few weeks to a couple of months for a pond to fully cycle and that's only if you have the right conditions: BACTERIA & PLANTS. You do not need "pond" plants. Hostas make good marginal plants with the pots in the water but the tops of the plants above the water. Just dig some up from your yard and plant them in well-rinsed, plain, non-clumping unscented clay kitty litter and put them in the pond. Watercress can be bought as a salad food at some grocery stores, just throw it in the pond and it will grow. Several type of Iris do well in ponds, if you have some in your yard, post pics of what they look like in bloom and we can tell you if they are the right type. That being said, I see you are in the UK, and here are combo packs of pond plants that you can just throw in and be done (no thinking required, planting depths are listed, just follow the instructions - these range in where they are planted in the water, see the chart below and read the description):
https://pondsuperstores.com/oxygenating-plant-collection/
https://pondsuperstores.com/wondrous-winter-pond-plant-collection/
Don't forget to buy baskets! Always replant into bigger baskets so the plants have room to grow.
https://pondsuperstores.com/round-2l-pond-plant-baskets/
For floating pond plants, ebay is the way to go. I just get mine from someone selling a mix like this which they wrap up in a paper towel and throw in a baggie in the mail and it works out great. No point in paying more, it'll seem like a silly small amount, but they reproduce real fast in a sunny spot.
https://www.ebay.co.uk/itm/133771490653
