Holy cow !!! No matter how many times I see the undersized Intex filters, I’m always amazed. My 400 gallon hot tub had a similar sized filter. For reference this is what I bought for me new pool. It’s 7 X the gallons but the filters are over 2 ft wide.
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The point is that it is going to take a lot of time for the filter to do its job. It will need to be cleaned often. When the process drags on, it’s Intex’s fault and not the process. Search around when you have some moments going forward and you can probably score a much bigger used system on FB marketplace / OfferUp for cheap. Many folks will be trying to unload them towards the end of the season when they don’t need them anymore. Just like boats, their value plummets in September.