help needed please guys

[JRcichlids]

i have a rack with 3x 3ft tanks and a 3ft sump aswell. instead of drilling the tanks could i run some type of pvc overflow instead ? heres a pic of the rack and tanks. not my pic but all is the same

 

[Andrew McFadden]

You could run an over flow box going down go each one till you vet to the bottom one and pump it back up to the top tank