Marinevet

Hello, Question about building a gravel base for hot tub. I ordered a 79" by 79" 700lb 300 gallon acrylic tub. I built a 8x8 foot area 5 inch deep with 4x4x8 wood enclosure. I went to get the gravel all they had was 1/2 mixed pea gravel. I did add a layer of 1 inch sand under 4 inch of gravel. Would this be enough to support the tub? Since it's enclosed by the wood will the gravel be okay to keep from shifting since it's not a huge tub? Thanks.