Substrate in high flow tank
So I am looking to do a low tech tank. The tank will be about 535g with corner HMF filters and an ultima pond filter that has intakes coming through the bottom of the tank. My plan was to use large amazon sword plants to help hide the corner filters. I also wanted to do some tall plants and some sort of carpeting plant. I am looking to avoid doing any gravel cleaning which means I need something where debris cannot penetrate. For now I am thinking of pool filter stand.
My biggest concern is that I will have about 10,000gph running in the tank between the two filters. The ultima intakes will be about 6in off the sand to prevent sand from getting in. Is there other heavy substrate I can consider that will work for low tech plants but be dense enough that waste/debris does not fall between the grains of substrate.