tank cover growth

[surgeon67]

I have a covered tank, in which the water level comes into contact with the acrylic. This has allowed algae to build up on the downside which limits my light transmission. This area is difficult to keep clean, and the snails don't seem to go up there much. Also, small bubbles collect on the underside along with organic stuff, much like skimmate in a cup. I was thinking of drilling a few small holes in the overflow to increase the drainage and hopefully lower the water level to teh point that it no longer contacts the cover, and would improve surface skimming. Any downside in doing this? The other way would be to restrict outflow from the return pump with a valve, but I'd think that wouldn't be the better option.

[ChaoticReefer4u]

sounds good to me because your water needs to turn over twice as much! good luck and get going........

[surgeon67]

sounds good to me because your water needs to turn over twice as much!

Twice as much as 20 x?

The water turnover rate won't be affected by the changes I'm proposing, only the water level. Are you saying I don't have enough turnover too?

[Sandworm]

Can you turn down the pump on the return?? In effect this should give the water more time to drain and in theory should lower the water on the drain grating. How far up the grating does the water go?? I wouldn't drill until you ran some tests to make sure.

[surgeon67]

The water level goes all the way to the top of the tank, and so does the grating. The overflow is a corner style with 12 slits about 3" tall and 1/4" wide each. The tank cover is immobile and the water goes to the level of the cover....in other words there is no air/water interface at the top of the tank, it's a water/acrylic interface.

Yes, I could put a valve on the return as I mentioned for the same effect, but it reduces my overall turnover rate, so I was thinking it wouldn't be the better way to go, but that's basically the question.

[surgeon67]

for what it's worth, I tried external compression on the return hoses to see how much of a flow restriction I would need to drop the level, and it was pretty severe. The tank flow dropped considerably, and I can't see how the pump would tolerate the workload very well. Next step is to call the tank manufacturer. But I gotta do something about the cover growth.

[Sandworm]

thats really strange, I have an overflow in my tank which also goes to the top of the tank. But in my case the water level never gets but halfway up the overflow , leaving me about an inch or so before the top of my tank. My tank turns over about 3800 lph and no matter how much water is removed from the sump, the level in the tank remains constant. I would definately talk to the manufacturer on that one.. IS the overflow filled up inside that area??? Or does the water go out of there fast once its gone into the overlfow..

[surgeon67]

Well, my pump runs at 2000 gph (7660 lph), so that's undoubtedly the issue. The overflow works fine, in fact I had to add standpipes to raise the overflow level to quiet the noise from niagra falls. The pumps work great, so I don't want to change them out, so I THINK drilling a few more holes in the overflow grill will solve the problem, but I'm obviously reluctant until I klnow I won't be burning any bridges.

[surgeon67]

Update...

Spoke with manufacturer about drilling the tank. I was told that if I did the warraty would be voided. Sooo, I suppose I'll be getting flow restriction valves on my pumps. I was also told that it isn't normal to have the water to the top of the tank, so I guess the pumps they sold me are overpowered for my tank. Oh well, worse problems to have I suppose

[1996 cobra]

what does your plumbing consist of---

head height?
pvc or vinyl

jus from what you said your return is larger then the drain on your tank. id say reduce the pump to a 1700 gph or even a 1200 gph and add a few power heads.

the automatic funnel will still occur but id say that at an average 4 foot head your still at 1500 gph or so maby a lil less.

you could also have a block in your drain line causing it to drain slower then the pump and the extra water in the main tank is a direct result of the slower drain. i dont think drilling the over flow would do you any good. worst comes to worst set up an external overlfow on the back or side of the tank to help creat a large drain from the main tank and dont put a return pump onto the external overflow and see if that helps at all. if you do it set it for maby 1/2 an in above the water lvl of the main overflow.

hope this helps justin

[reefeng]

If you are going to use a valve try to locate a PVC gate valve. Flows can be extremly difficult to control with ball valves. At some point in time once you know the flow you could put in an orifice which would always allow the same flow. Before you put in the valve though check the pump mfg. instructions / technical info. to make sure there are no issues with pumping against the head pressure if you have to keep the valve partially closed.

[surgeon67]

what does your plumbing consist of---

head height?
pvc or vinyl


head height ~ 50", pipes=vinyl


jus from what you said your return is larger then the drain on your tank.

Nope, the tank inflow is greater than the overflow capacity. The overflow works fine up to its max, and the drain empties it quite well, in fact I have to add a standpipe in the overflow just to quiet the noise from the waterfall back there. The problem is that there is more water in the tank than can flow through the overflow slits.


id say reduce the pump to a 1700 gph or even a 1200 gph and add a few power heads.

yep, that's gonna be the plan. I originally had 4 400gph PH in there, but had to take them out because they didn't stand up to the wavemeker.


the automatic funnel will still occur but id say that at an average 4 foot head your still at 1500 gph or so maby a lil less.

Can't increase the head height since I can't lift the tank or lower the pump.


worst comes to worst set up an external overlfow on the back or side of the tank to help creat a large drain from the main tank and dont put a return pump onto the external overflow and see if that helps at all. if you do it set it for maby 1/2 an in above the water lvl of the main overflow.


Now THAT would work quite well, except for the difficulty of placing the overflow in the covered tank... no place to hang it on the back. I might be able to rig something through one of the cover lids, but it wouldn't look very good. I've been trying to design a corner overflow that would fit through the lid, and not require a hole drilled in the tank, and still not be obtrusive, but no luck so far. Meanwhile the pump return valve will have to do.

[surgeon67]

try to locate a PVC gate valve. Flows can be extremly difficult to control with ball valves.

Is that a standard item in a plumbing supply dept at home depot or a specialty/aquarium item? Compatible with vinyl tubing, or do I need PVC?

[reefeng]

I would try Home Depot or Lowe's if you have them. As usual with threaded fittings use teflon tape. You could also give either an Ace Hardware or True Value Hardware a shot.

[1996 cobra]

1996 cobra wrote:

jus from what you said your return is larger then the drain on your tank.


Nope, the tank inflow is greater than the overflow capacity. The overflow works fine up to its max, and the drain empties it quite well, in fact I have to add a standpipe in the overflow just to quiet the noise from the waterfall back there. The problem is that there is more water in the tank than can flow through the overflow slits.


we said the same thing jus a lil different. what i implied tho was that your return line is flowing at a greater rate then your drain can handle. thats why i followed up and confirmed with your own opion that you should get a smaller pump :)


im not positive but most gate valves at home depot come in iron and copper( ie solder or compression fighting) he would have to go to a plumbing supply houw to possibly find a plastic gate valve or orde rit off marines depot. a regular compression should work snice alot of them are designed to be integrated into the freezer lines a s aregular and alot of freezer lines are plastic.

justin

[reefeng]

It's worth it though to investigate whether or not the current pumps can run with pumping against the backpressure a valve will create because it is a much cheaper solution that replacing the pumps.

[1996 cobra]

i really doubt any pump would do well pumping against any back pressure. it would have to work harder then normal to pump against the addittional force comming back down. i dont know maby it can handle it but then the question come sup for how long.....


justin

[surgeon67]

well, in theory, a valve placed in line withthe pump that restricted the flow would be no different as far as the pump was concerned than a greater head height. If the pump can handle an 8' head height for example, then the same effect would be achieved by having 0' head and a valve adding the same amount of flow resistance. Yes the pump works harder, but it should handle it OK, I think.

One other thing that could work but in my case would be VERY difficult due to the layout would be to change to PVC pipe and add some 90 degree angles. Each turn adds about 1' of effective head height rather than the smooth curves of the vinyl tubing I have now. When I get my room remodeled all of my plumbing will be in a 5' x 10' room out of view, so I can do all that stuff. Right now I have to SQUEEZE everything under the tank in the stand (chiller won't fit tho).

[1996 cobra]

tru with the pvc but you cant know how much restriction it will cause against the pump with a valve. i have a feleing closing the area of flow would cause a much greater back pressure then some simple head height. cant be sure id call the manufactor like noted above.

justin

[reefeng]

If you would like to try something really easy, use a c-clamp on your vinyl tubing. You can clamp this on you tubing and as you close down on the clamp it will restrict flow through the hose. I have tygon tubing and this works well. In so far as damaging your hose you will not need to close off all the way and this wouldn't damage the hose unless you closed down and really compressed the tubing. If you find that you want to cut in a valve on the tubing a PVC valve does not need much support and it could be connected in the line with hose barbs.

[surgeon67]

I tried the same idea by just compressing it with my hands for a few seconds, and it worked very well. Obviously I can't hold it very long, and isn't much of a long term solution, but you're right, external compression will do the job.

[surgeon67]

Honesty compels me to relay the following fact... I am an idiot. After all this discussion, and all the time spent thinking about this, I finally stumbled across a solution that should have been stunningly obvious to me. My "main pump" is really 2 1000gph pumps. I turned one of them off: problem solved. :oops:

I thought you could all use a good laugh.

[1996 cobra]

W O W..........

[surgeon67]

yeah, that's pretty much what i thought, except mine was followed by a string of expletives at my oversight. Just goes to show, you gotta be careful, or something will come along and humble you but good.

The other thing I keep thinking is what my father would say to something like this: "Son, I don't b'leeve I woulda told that!"