# Rena Filstar XP4 - low flow. Priming problem?



## majorwoo (Dec 25, 2012)

I have 2 used XP4's. My previous Eheim was a cake walk, but I can't tell if I'm just having trouble priming them - or if I've got an equipment problem.

I've tried following several guides online, but it's difficult to get them running at full power when I first hook them up/clean them, and after a few days it seems they have lost their flow. I believe I've got an air leak somewhere. After cleaning the filter yesterday( I had decent flow then) I had nearly no flow today, so I took this picture of the canister under the tank - should there be a bit of air at the top like this? I don't think so - hence my belief I'm getting air in the line somehow.










I'm wondering if the baskets should be fitting tighter to the top motor housing - they seem a bit sloppy in there, I question whether the water is really being sucked in through the bottom properly as well.

Thanks for any input!


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## majorwoo (Dec 25, 2012)

Oh, and for the record, my most successful priming method:

Open quick disconnect
remove filter, clean, return under tank empty. 
Reconnect lines
close disconnect (both intake and spraybar are below water level)
Allow water to fill canister before turning on

The water seems to stop right about where you see. If I mess around tilting it open/close it a lot I can sometimes get it a little higher (and I seem to get more flow then too).

The cover is screwed on tightly to the intake priming cap that I had to use the first time to prime it.


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## umdterps96 (Oct 21, 2010)

If you unlatch the front two the water will fill up all the way. Be quick though to lock them back up so water doesn't rush out


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## majorwoo (Dec 25, 2012)

umdterps96 said:


> If you unlatch the front two the water will fill up all the way. Be quick though to lock them back up so water doesn't rush out


Thanks, that was in incredibly simple idea I feel I should have thought of 

Good news, is the water filled all the way up. Bad news, still low flow. I need to break them down again and maybe run them without the final sponge. It seems to get dirty very fast, maybe it really is just blocking my flow.

I really feel like the baskets are not stacking up/fitting tight to the motor housing and the water flow is bypassing normal routes and just getting sucked right back in there - which is why that final filter is getting so dirty and the ones at the bottom that should get dirty first don't seem to be.


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## umdterps96 (Oct 21, 2010)

What media are you using? Make sure your not over filling them. The baskets should sit level


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## mstamper (Jun 5, 2012)

If you had trapped air in the filters they would be making a loud noise. I have had trapped air in mine and you know when there is air in the line and canister.

Your low flow may be from dirty impellers and the cavity where the impeller sits. You also need to look at how your hoses are laid out. If you have low loops that sit below the filter pump is not as efficient and will slow down your flow in the tank. The instructions for setup specifically state to have the hoses setup cut to fit. They don't need to be exact but you definitely don't want a lot of extra hose. 

Too much polishing pad filter can slow down the flow a ton as well. I only have about a quarter to a half inch of dry fine filter floss in the top of my baskets, any more and it restricts the flow.

Hope you get it figured out soon.


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## majorwoo (Dec 25, 2012)

Well, I did what I should have done, and took the sponge that looked old and dirty out of the system. Much more flow now, but the question remains will it hold up over a few days. I do think I've got more flow now then I did when I first hooked them up, so that's a good sign.

*added*
I've often gotten pretty good flow from them before that tapered off over a few days.


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## majorwoo (Dec 25, 2012)

There are 4 baskets, each divided in half with the little plastic pad. In each filter I have:

Bottom basket
lower: 2 sponges that came with it
upper: 2 sponges that came with it

2nd basket up:
lower: mostly full of ceramic ring media
upper: mostly full of ceramic ring media

3rd basket up:
lower: mostly full of a plastic bio media - sort of a multi edged star shape
upper: ceramic ring media

top basket:
lower: filter floss
top: (now removed) I believe it was a polishing pad - the sort of sponge/pad that had 2 side sort of glued together

All baskets sit level on the one below them.

I have already cleaned the impellers out, so nothing really bad in them - just some slime which I understand is to be expected.

As far as noise, they are definitely louder then my old Eheim classic 2217, but they don't gurgle/splash or anything like that. I do sometimes hear a air pressure sort of hissing sound - which I've always thought was air trapped in the line. The are not too loud IMO - I don't normally run an air stone but right now as I'm fighting Ich with 84+ and some paraguard/UV I am running one, and it's the loudest thing in the room.

I'm hopeful that the little trick about opening the filter and letting more water in will prevent the air/hissing sound I sometimes hear - we will see.

My stand is 24" and the Rena's are on the floor under it. Because they are so tall, the hoses do dip down from the top of the Rena to go under the edge of the stand and run up to the tank. They are the original hoses that came with the pumps that were cut down, so I highly doubt they are too long. I have questioned the little u-turn they have to make to get to the pump, but it was my belief that it would only make my life difficult for my first prime (which it did, but now that the lines are primed I've not had much trouble with that.

Thanks to everyone for your advice. I've had tanks a long time but these are only my second and third canisters, so it's good to have people checking things for me


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## dmagerl (Feb 2, 2010)

Make sure you clean the hoses and intake tube. Those can get really clogged with goop.

Also, with mine, I had all sorts of trouble with it maintaining flow and sucking air until I moved it onto the floor next to the stand. Rena recommends a minimum of 24" between the top of the water and the top of the filter. If its less than that, you might have problems. I did.


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## devilduck (May 9, 2012)

I find that filter floss clogs up pretty quick in my XP's I stopped using them and use the top basket for Purigen and sometimes carbon.


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## majorwoo (Dec 25, 2012)

Thanks. The stand is 27" and the tank is 24" and the filters are on the floor under the stand.

If you'll pardon my crude paint drawing 










I thoroughly cleaned the tubing a few weeks ago when I set these filters up, I am wondering about taking the spray bar apart and seeing if it has some junk in it. So far today my flow has remained strong.


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## majorwoo (Dec 25, 2012)

devilduck said:


> I find that filter floss clogs up pretty quick in my XP's I stopped using them and use the top basket for Purigen and sometimes carbon.


I was originally running one filter with filter floss and the top pad, and the other without. Both were slowing down dramatically. I put filter floss in the second one when I took the top pad out, we'll see how it goes - I may end up having to take it out. With it being on the top basket it's fairly easy to rinse out without disturbing the rest of the bio media so I may just leave it for now.

I've heard really good things about Purigen - I may try some. I'm wondering if it would remove Ich from the water at that stage of their development. Sounds like I have something to go read up on


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