Tests:
1. Eheim 1262 with ER mod: air draw = 3 lpm, 20L/89s or 214gph.
Observations: The air meter had rampant fluctuations. The strange thing to this test was that the pump slurped and pumped water very slowly. It appeared to be cavitating. The whole pump rocked in the tub as the pump was slurping.
2. Eheim 1262 with ER mod: air intake off, 20L/25s or 760gph.
3. Eheim 1262 with Cerreta mod: air draw = 5 lpm, 20L/63s or 302gph.
Observations: The air draw was very steady at 5 lpm, no fluctuations like the ER mod produced. No cavitation or slurping noted with the Cerreta mod plumbing.
4. Eheim 1262 with Cerreta mod: air draw off, 20L/24s or 792gph.
5. Eheim 1260 with ER mod: air draw = 3 lpm, 20/85s or 224gph.
Observations: The same cavitation and slurping occurred. The air draw was rampant.
6. Eheim 1260 with ER mod: air draw off. 20L/25s or 760gph.
Observations: No slurping or cavitation. Air draw was consistent.
7. Eheim 1260 with Cerreta mod: air draw 5lpm, 20L/63s or 302gph.
Observations: No slurping or cavitation. Air draw was consistent.
8. Eheim 1260 with Cerreta mod: air draw off. 20L/26s or 731gph.
Conclusion:
I was very surprised by the testing. There was no significant difference between using the Eheim 1260 or 1262 pump when comparing flow output with the air flow off regardless of which mod was used. Compare values of test 2, 4, 6, 8. Likewise, no significant difference was observed in flow output when the air valve was wide open between the two pumps when the same plumbing mod was used. Compare values of test 1 vs. 5 and 3 vs. 7.
Strangely the slurping and cavitation of the ER mod did create a statistically significant difference in flow output when comparing the same pump fitted with different plumbing mods. Compare values 1 vs. 3 and 5 vs. 7. I did repeat this test several times and they all slurped. The cavitation did create a wide variety of times which were averaged to get the reported values. The cavitation did affect the speed of continuous water flow. I have no rational explanation for why the cavitation occurred in theses tests. However it should be noted that cavitation does not occur when the pump is used with salt water and attached to a skimmer body.
So, it can be concluded that there is no significant difference between the Eheim 1260 and Eheim 1262 pumps with regards to air draw, current draw, power consumption, or water throughput. These pumps are identical in my observations and tests. The only differences I know of is the volute on the 1262 is larger than the 1260 and this explains the 40% volume increase in flow when comparing the two pumps. However, when used as a skimmer pump they perform the same. I do believe that the 1262 does have more windings wrapped around the motor. This would explain the slight increase in current draw however, in these tests with low head pressures. I could not detect any differences. It would be interesting to see if the 1262 does outperform the 1260 in larger and taller skimmer bodies that exert more head pressure on the pump.
These tests were fun and easy. I was surprised to see that my plumbing mod did not decrease the flow output when compared to the larger diameter of the ER mod. I also thought it would be a great challenge to find a conversion adapter from metric to US piping. However, the H&S volute is not a threaded device and the material is much thicker and stronger than the original Eheim volute. Therefore, shoving a ¾†MPT pipe into the volute hole using pipe thread compound to form a seal worked just fine. In fact I have had this pump in use now on the ER 180 for several hours without leak or fail.
Another caveat worth mentioning is that the output of the Eheim 1260 with Cerreta mod has a ¾†pipe threaded into the output threads. The ER mod had a metric to US adapter (or ER just did some CNC milling of 1†pipe) to seal the union on the output to the outside of the Eheim pump outlet.
The reason I mention this is because it means there could be a very simple way to save some money and retro fit an Eheim 1262 to your existing ER skimmer. Recall that the results showed no significant difference between my mod and the ER mod in terms of flow throughput. Therefore, even though I used ¾†threaded pipe on both intake and output, that means it will work fine and there is no reason to try and find metric to US adapters to connect plumbing to the external parts of the volute and outputs. Also, the only reason I had to buy the H&S volute is because the Eheim 1260 does not come with the proper internal orifice that permits the skimmer to function properly. But, the 1262 does. So that makes for a very simple DIY Eheim pump project.
Eheim Pump DIY project:
1. Eheim 1262 pump $140
2. Two ¾†to 1†slip x slip bushing $2
3. One ¾†x 5†MPT to MPT Sch 40 pipe $2
4. Two one inch KBI unions $10
5. One 1†elbow slip x slip $0.50
6. One ¼†nipple elbow for air line tubing
7. ER new style pinwheel $30 (no reason to buy whole impeller, just cut the vanes off the stock impeller and push the ER PW into place. Or you can remove your old PW from the GenX impeller and use it, or you can make a mesh wheel.
Total cost should be around $200 with glues and shipping and miscellaneous stuff.
The build should be easy enough, but you need to cut item number three so you have one 3†piece and one 2†piece. Use the two inch piece on the output and glue bushing and union. You need to drill a hole into the 3†pipe to accommodate the air line elbow. One side of the elbow needs trimmed. Then press into hole and use acrylic glue to seal in place. Silicone may work here. Next, glue bushing to slip end of pipe. Glue elbow to bushing. Glue a short section of 1†PVC pipe to elbow. Glue union to 1†pipe. You may have to adjust some of these lengths to make sure the union spacing and heights are correct to fit to the skimmer body. Not too hard if you have the tools.
Some final pictures:
Skimmer running with Eheim 1260 pump and Cerreta mod with ER new style pinwheel. Notice how the foam extends down further in the body here? I used a 1†45 degree fitting and angled the foam trajectory downward.
Without the 45 degree fitting.
Airflow test without the silencer in place. Draws 13lpm (just cleaned cup, will be higher tomorrow). Eheim 1260 pump and Cerreta mod with ER new style pinwheel.
Airflow test with silencer draws 12lpm.
