Red Dragon 3 Mini Speedy 50 Watt Pathetic Performance

[AZRippster]

It was suggested I post this here. The distance from the pump to the venturi inlet is about 20". The previous pump in use that rocked was an Iwaki MD40RLT, half the output of the RD3 Mini Speedy 3 50W, but pressure rated. This was previously posted in the Lighting and Filtration forum:


I'm currently in the process of a rebuild on my 450G tank. A couple of the upgrades were a Red Dragon 3 Speedy 150 Watt for the main system's return pump and a Red Dragon 3 Mini Speedy 50 Watt for the LifeReef VS3-36 Skimmer. I had previously been running Iwaki for these services. The main reason for the change was due to the heat transfer of the Iwaki's. The RD3 Speedy 150 Watt is doing a fine job and very close to the performance of the Iwaki MD70RLT, however the RD3 Mini Speedy 50 is simply pathetic. It's rated for twice the output of the Iwaki MD40RLT (and more than twice the cost), yet can't even fill the skimmer body. The line from the RD3 Mini to the Skimmer's venture intake is about 20", yet it can't even drive with enough force to fractionate. I was wondering if anyone else has had an issue with the performance of a Red Dragon 3 Mini Speedy 50 Watt, or do you think I may have just gotten a lemon and need to return it?

Thanks!

 

[slief]

The RD3 50 is a flow rated pump that doesn't do well with head pressure. It has a max cut off of 12'. It's designed for smaller systems as well as feeding media reactors.

While the VS36 is a venturi skimmer, I suspect the venturi valve is creating more head pressure than you realize. It's not just the 20" height to the venturi valve. The valve itself creates a fair amount of head pressure/friction loss as do the fittings going into the skimmer which is likely why they recommend the pumps they do as opposed to other pumps that have higher flow and less power consumption. Having built mezzei based skimmers in the past, this is something I often encountered. The pumps pressure output needs to match the valve. The same goes with Beckett skimmers but venturi based ones are generally a bit more forgiving.

The recommended pumps for that skimmer are pumps that deal with higher pressures exceedingly well in that they don't fall off as fast as the pressure increases.

The Blueline 30HD-X is a 90w pump rated at 1100 GPH and has a max head 13'.
The Blueline 40HD-X is a 120w pump rated at 1270 GPH and has a max head of 13'
The Iwaki MD40RLT is rated at 750GPH at 4' but has a Max Head of 21.3'!
The RD3 50 is a 50w pump rated at 1320 GPH and has a max head of about 12'.

Now, your Iwaki is a pressure rated pump and the Magdrive 18 that they recommend with the internal skimmer is effectively a pressure rated pump. The specs on the blue lines above are based on the non pressure rated pump which has me curious is the model they actually recommend is a pressure rated version.


Interestingly, the MAG 18 (recommended for the internal version) produces 575GPH at 15' of head. It also draws 150 watts. You can't really expect a 50w pump to generate comparable flow to any of those pumps when you start to factor in head head/friction pressure. I have a call into Life Reef but I already know the reason for your issue. The only pump that would be comparable to any of those that are recommended by Life Reef would be the RD3 80 but its not pressure rated either and while the flow numbers of the RD3 50 at 0' would lead you to think otherwise, in the end, you may have brought a knife to a gun fight and may be judging the RD3 50 unfairly simply because the application it's being used in may require a different pump.

Once I hear back from Lifereef regarding the head pressure generated by the VS36's Ventui valve I will update you.

By the way, Luke reached out to me on your behalf and I sent you an email immediately and that was before I saw this thread.

 

[slief]

One thing that stuck out at me is that you mentioned the RD3 50 can't fill the skimmer body. Are you talking about filling it with water? If so, it's not supposed to fill it with water without closing the gate valve on the skimmer itself and going from the Iwaki MD40RLT to the RD3 50, you are going to need to close the valve substantially more with the RD3 50.

I just spoke to Life Reef and he and I both agree that the RD3 50 may not be the correct choice for that skimmer but it really is going to come down to the amount of bubbles being generated within the body. Send me your phone number so we can chat. Ideally, I would like to do a facetime with you.

 

[AZRippster]

Scott,

Thanks for the reply.

I'm starting to realize I made a costly selection to replace my Iwaki MD40RLT that ultimately will not work. I'm guessing the Venturi is adding quite a bit. I emailed Jeff as well this morning but haven't heard back from him. I know on his website regarding his skimmers he states, "œANY PUMP CAN BE USED" and "œUSE ANY PUMP YOU WANT TO USE", however that is obviously not quite the case. He likes the Blueline, basically a Panworld, and IMO probably due to the price point versus the Iwaki. MAG pumps are rock solid, but transfer too much heat. I "œhad" one of those driving my manifold but I'm going to replace it as well. I wanted the RD3 80, but at the time I couldn't seem to find it in stock. The difference in price between the RD3 50 & 80 definitely had me wanting the 80 but couldn't find it.

I've been avoiding DC pumps for quite a while due to reviews by many folks regarding head pressure issues but after deciding to redo our tank, I figured I would take a risk. The RD3 150 appears to be performing on par to what I expected. By taking a gamble with the RD3 150 that more than doubles the output of the Iwaki MD70RLT (Max Head ft: 31.8), I was hoping the same would work with the RD3 50 vs Iwaki MD40RLT.

With the Blueline 40HD-X with a max head of 13' and the RD3 50 with a max head of 12', I thought it would be much more comparable. Au contraire, huge difference. The Blueline 40HD-X is what Jeff originally recommended to me when I bought the external VS3-36 but opted for the MD40RLT (Japanese motor) instead.

As far as the gate valve, it's where it sat with the MD40RLT. I know I need to adjust the valve to raise the water in the column, but seeing the amount of bubbles being produced, which is barely, it was immediately apparent I had an issue.

Sorry, I'm an Android guy.

Now I have to explain the loss to the wife, not fun.

 

[slief]

Scott,

Thanks for the reply.



I've been avoiding DC pumps for quite a while due to reviews by many folks regarding head pressure issues but after deciding to redo our tank, I figured I would take a risk. The RD3 150 appears to be performing on par to what I expected. By taking a gamble with the RD3 150 that more than doubles the output of the Iwaki MD70RLT (Max Head ft: 31.8), I was hoping the same would work with the RD3 50 vs Iwaki MD40RLT.

With the Blueline 40HD-X with a max head of 13' and the RD3 50 with a max head of 12', I thought it would be much more comparable. Au contraire, huge difference. The Blueline 40HD-X is what Jeff originally recommended to me when I bought the external VS3-36 but opted for the MD40RLT (Japanese motor) instead.

As far as the gate valve, it's where it sat with the MD40RLT. I know I need to adjust the valve to raise the water in the column, but seeing the amount of bubbles being produced, which is barely, it was immediately apparent I had an issue.

Sorry, I'm an Android guy.

Now I have to explain the loss to the wife, not fun.

The RD3's are not actually DC pumps. They are variable speed AC pumps that send high voltage but low current AC power to the motor block. That said, you can't just look at flow numbers when comparing one pump to the next with Venturi skimmers. The flow curve has a big impact and one thing is for sure, all the RD3's are conservatively rated but as I said, for venturi applications, other factors need to be taken into consideration when choosing the correct pump.

That said, Jeff may be updating the flow specs on the skimmer products page as he suggested 1800 GPH for that skimmer when he and I spoke. In the end, I never would have recommended this pump for that skimmer. An RD3 80 would have been a better choice if that was the path you were wanting to go.

Now, on the flip side, while I wouldn't expect the same volume of bubbles in your skimmer compared to that Iwaki, I would suggest raising the level by closing the gate valve and give it 24 hours to settle down and see what kind of foam it generates. It may not be as bad as you think. I can't say honestly because you are doing something with this pump that I haven't tested but it might not be as bad as it appears right now once it's settled in some or at least adjusted.