If you do not want to go with 1.5 you can go with 1.25. At 4' head the 1.5 will give you 1326gph while with 1.25 you get 1293gph. For a loss of only 33gph I would go with 1.25. I am running mine with 1.25 and have had no problems at all.
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120 Reef 20 DIY sump
500watts 14k MH with 220watts actinic vho
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