Question about evaporation

[frankthetank]

I'm not even going to say it... I have been saying I was going to have my fuge up and running in a few days for a few weeks. But in all honesty, I should have it going in the next few days for real.
Have I heard wrong or do you only have to add water to the return section of your fuge/sump? Does water evaporate in the DT too?
I swore someone told me that when you have a fuge, water does not evaporate in the DT... but I cannot understand how this is so?

 

[al mc]

Water evaporates in any tank (DT or Fuge/sump) that contacts air. However, I only add water back to the system in the sump. I have an automatic top off system. I started by just putting a piece of tape on the sump glass at the level of water when my S.G. was 1.026 and just added
RO water that had a pH adjusted to 8.3 back up to that line once daily by
using a gallon pitcher.

 

[ifirefight]

Your display tank's water level is set by the draining overflow box. That
water
level is maintained all the time, no matter what.
Your sump's water level will be the one that fluctuates as evaporation
occurs.
If you use baffles in your sump, the water level will stay constant in all
those
zones EXCEPT for the return zone where your return pump is located. This is
the
area that will continue to lower over time.

 

[thangbom]

humm.. never did the ph thing.. actually never even heard of adjusting top of water except if it was lime water ( kalkwasser to sup. calk/alk) whoever told you that dt will not evap if you have a fuge is full of it... they are both tied togerther ar'nt they?? so how the heck is one going to evap and one not.....?... anyhow both will evap.. you can top off at either spot cuzz they both feed each other as to say (dt overflow to fuge, fure return pump to dt) most people top off in the return section as to difuse the ro/di water everywhere faster as to not have one spot hold a lower sg for a period of time... i have a tom's aqualitfter pump and a digital timer that tops my water off... it pumps .9 gals a day into the return section 2x a day... ( i also put pickling lime into my ro/di tank to sup calk/alk) and thats about it for top off... the holding tank is just a 13 gal trash can in the stand that a fill when it is empty.. i rinse it off 1x a month to ride of the kalk scum...
YzGyz

 

[frankthetank]

Originally Posted by ifirefight
Your display tank's water level is set by the draining overflow box. That
water
level is maintained all the time, no matter what.
Your sump's water level will be the one that fluctuates as evaporation
occurs.
If you use baffles in your sump, the water level will stay constant in all
those
zones EXCEPT for the return zone where your return pump is located. This is
the
area that will continue to lower over time.
See this is what I cannot get my mind to undestand! How does the water level in my DT stay the same all the time, no matter what?
I fully understand why the water level in my skimmer and fuge section remain constant, and I understand why my return level would evaporate... but I do not understand how the DT water level remains the same. Completely baffles me!!

 

[thangbom]

=^b well it's like this... the return pumps pumps water into the tank at x rate... keeping the dt tank 'full' which in turn feeds the overflow that dumps water into the fuge... so in essence the dt tank is constantly at the same water lvl... ( as long as the return pump keeps pumping the same x amount of water ) the fuge do not keep the same lvl cuz it it getting 'robbed' of it's water ( whatever is left) to feed the dt... so that is why you see you water lvl lower when you lose water due to evap...
hum.. that seem kinda not too clear...
ok.. the overflow feeds let say a given gph that dumps into the fuge... we will call that 10... now the return pump will pump also pump a given gph which will also be 10.. the dt will hold 100gals ( just cuzz it's a easy ##) .. so.. this will mean that the dt will receive a constant 10 in and 10 out which will keep it the dt at constant 100... now we add in that it will evap .9 gal a day... but.. that .9 gal will not physically show in the dt becuase of the return pump... cuzz the return pump will keep it full by 'robbing' the fuge/sump of the .9 gals .... which is why the fuge/sump seems to be the only one that eveps... gezz this is harder to explain then it really is...
HTH
YzGyz

 

[frankthetank]

Ha!
Well I understand that the DT drains x amount of water and that the return pump pumps that same x amount of water back. But I don't see how that keeps the DT from evaporating and lowering.
Wait a minute... maybe I'm seeing it??? Because the same water is circulating down to the sump, and then back up that keeps the water at the same level. So the return section is the section that fluctuates. Still doesn't make complete sense to me. Guess I have to live with it though.

 

[thangbom]

that is exactly it... cuzz the only place that can actually change is the return section... the dt lvl is perdicated on the overflow height.. it will keep that high as long as water is present... that is where the return comes in.. it will do just that.. keep water present in which will keep the dt water constant... the return section is the only place that will fluctuate cuzz there is nothing that will hinder it from flutuating... thats what i ment when i said it get 'robbed' via the return pump..( the return pump just keeps pumping as long as it's primed) nothing is keeping it from holding the same lvl.. so when water evaps.. it seemingly take water out of the fuge to keep the dt full...
YzGyz

 

[reefking121212]

Originally Posted by FranktheTank
See this is what I cannot get my mind to undestand! How does the water level in my DT stay the same all the time, no matter what?
I fully understand why the water level in my skimmer and fuge section remain constant, and I understand why my return level would evaporate... but I do not understand how the DT water level remains the same. Completely baffles me!!
theres basically "a drain" at the top of the tank

 

[trigger11]

Picture it like this. Here is an extreme example.
DT is empty.
Return pump in fuge is pumping water up to the DT. While the return pump is pumping it is lowering the water level in the fuge as the DT starts filling up. In order to be able to get the DT full of water you would have to add water to fuge or it will run out. Now, as the DT gets full of water it hits the overflow. The return pump in the fuge is still sending water to the DT so in essence the water level in the DT is always going up. Its just that it goes to the overflow so stays at that level. So now as the water evaporates you have to add water to the fuge.
Hope this helps.
~Trigger

 

[shark bait]

ok, i have about 300g of water with sump. I have a blue line across my sump at the 9" line as I need 6-9" of water for my skimmer to work at peek level. BUT my sump can run with 3" of water because my return line is in the bottom of the sump. If I keep at least 3" of water in my sump it will not change the level in my main tank. This is because of the over flow needs to be at a normal level to flow in to the over flow and in to the sump. So water will be loss from the tank and sump, but you will only see it in the sump for the reasons above. I hope this gives a good visual...