codeigniter 3 merge 2 table with pagination

I have 2 tables products and api_products i want to merge these 2 tables with pagination. I am getting issues with pagination when merging .

$internalProduct = $this->Product_model->listprodcts($limit, $offset);

$apiProduct = $this->Product_model->get_api_products_from_db($car_make_url, $car_model_url, $car_year_url);