• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Topping up open tank

jameson_uk

Member
Joined
10 Jun 2016
Messages
879
Location
Birmingham
I currently have a little breeding box that is a bit like a HOB on my Juwel tank. This means the front flap on the lid is open a little and I have been surprised by the amount of water I have lost to evaporation.

I am considering an open tank in the front room and was wondering about evaporation. As I understand it, only the water evaporates leaving behind all the minerals etc. So if I replace the evaporated water with tap water my GH would slowly but consistently rise?

I see lots of posts on shrimp forums about only topping off with RO but haven't really seen this mentioned on aquascaping forums.

Is this something I need to consider or just top up with tap water and don't worry?
 
Technically you would have to use RO water not to influence it.
However through adding EI ferts and doing waterchanges you will be adjusting all the time and get to some kind of balance.
Plants will be using minerals too. (It''s not the Dead sea................., yet :))
 
I top off with RO, but I don't do 50% weekly water changes and I have it kicking about anyway. I think low tech and open top is perhaps a less common combination? If you were doing low tech smaller/infrequent water changes might be worth looking at RO or bottled water with a low TDS. Or atleast using a TDS pen to keep half an eye on it. What you're keeping, what your tap water is like, water changes, and how long you keep a tank running etc. probably all factor into whether it's an actual issue or a theoretical one.
 
My tanks are all open top. I have more evaporation in the winter than in the summer due to the temperature difference. I never top up. I just do the weekly water change and in my case the water level never goes down too within a week for the tank not to function although it can go down substantially. I've gone on holidays from 2 to 3 weeks and the tanks have managed....When I come back the outlets may be splashing on top of the surface due to loss of water but extra oxygen exchange is no harm when one is away. I have also set up my tanks in a way that they can take the reduced water level.

If you are planning not to do water changes on a weekly basis, which I don't recommend for the sake of the fish, then RO water is probably best. Regardless, I personally find it hard to convince myself that dilution is an alternative to removal.

On a side note, open top tanks are best due to the possibility of growing emersed plants, which has a major positive effect on the water quality and mineral buildup due to evaporation or anything else is not easily achieved when you have a mass of plants that have access to aerial CO2 growing like crazy.
 
I currently have a little breeding box that is a bit like a HOB on my Juwel tank. This means the front flap on the lid is open a little and I have been surprised by the amount of water I have lost to evaporation.

I am considering an open tank in the front room and was wondering about evaporation. As I understand it, only the water evaporates leaving behind all the minerals etc. So if I replace the evaporated water with tap water my GH would slowly but consistently rise?

I see lots of posts on shrimp forums about only topping off with RO but haven't really seen this mentioned on aquascaping forums.

Is this something I need to consider or just top up with tap water and don't worry?

On my Aquascaper 900 which is 200L and I lose around 10L of water weekly.
I do use an AutoAqua Smart ATO micro with a water container underneath my aquarium that keeps things topped up for me.
http://www.autoaqua.com.tw/en/sato-120p.html
I was always sceptical about optical sensors alone so used a Tunze Osmolator on my marine as it was hidden out of the way in my sump but when it came to an open top with external filter this wasn't going to work. I haven't had a problem in over 2 years with the AutoAqua's and there have been 3 running in the house. Keep the sensor clean and you're good to go in my opinion. They have gone up quite a bit since I brought mine though! :woot:
https://www.tunze.com/en.html?user_tunzeprod_pi1[predid]=-infoxunter036

Personally I've never had a problem apart from when I removed an ATO when moving some things around; the water level dropping over the week was a lot more than you think and was quite unattractive to look at.
 
the water level dropping over the week was a lot more than you think and was quite unattractive to look at.

Yes, it is unattractive to look at and it tends to have some sort of psychological effect on one's brain, guilt perhaps...for it is time to do a water change. At least that's what my head concludes every time. Doing a water change when the level is too low is better than topping up until one gets around to doing a water change. Alternatively, keep the tank lid on.
 
Yes, it is unattractive to look at and it tends to have some sort of psychological effect on one's brain, guilt perhaps...for it is time to do a water change. At least that's what my head concludes every time.
That 9L (about how much I lose weekly) on an EA aquascaper 900 is around 20mm which to me is a lot and does have that psychological effect on my brain but I think that's OCD :pompus:
.9 x .5 x .02m LxWxH = .009 / 9L (not taking glass into account I know)
I accept that's over the whole week but even over 2 days that's nearly 6mm which my eyes spot :wideyed:
If you're going for a rimless aquarium I think that nice consistent water level of 12-15mm (maybe even a bit less ;)) below the top of the glass is the whole reason to; surely? - especially if your aquarium is (almost) perfectly level - water doesn't lie afterall.

Doing a water change when the level is too low is better than topping up until one gets around to doing a water change.
After reading my response do you understand what I'm saying?
I usually do a WC every 7 days which is my aim but sometimes more often and sometimes it will slip to day 8 or 9 but that's unfortunately out of my control :sorry:
 
surprised by the amount of water I have lost to evaporation
Over time topping up with tap water will increase TDS. However as stated above with weekly water changes or there abouts and extraction of minerals by plants there will be little impact on TDS. Do you still have very soft Brummy water. I used to live just outside Birmingham's water supply area and had liquid rock from South Staffs water. I use rain water its free, RO water is for the steam iron.

Thought about open top tanks but always concerned about fish jumping out and high room humidity from evaporation. Surprised by evaporational loses even from a closed tank.
 
Hi all,
Surprised by evaporational loses even from a closed tank.
My wife already blames the house plants for the condensation in the house, if I went for open-topped tanks I'd definitely be homeless.

I think some of the differences people find depends on how warm your house is, but you get more water loss in the winter, even from closed tanks.

We don't have our house as warm as a lot of people do, so we start off with a larger differential between tank and room temperature, which increases water loss.

There is also the differential in humidity between the air immediately above the water surface (fully saturated) and the humidity of the air in the room.

When cool, damp air comes into the house, via open windows and doors, it warms and the relative humidity falls. There is a really useful <"relative humidity calculator"> on the Lenntech web site.

I put 5oC and 100%RH as the outside temperature/humidity and 23oC as the internal temperature. The 100% saturated air coming in contains 5.74 g/kg of H2O, but by the time it has warmed up to 23oC it is only 33% saturated, and could potentially hold 17.6g/kg of H2O.

As soon as you get some temperature variation, or if you don't have good double glazing, that is a lot of condensation on the windows.

cheers Darrel
 
Hi all,My wife already blames the house plants for the condensation in the house, if I went for open-topped tanks I'd definitely be homeless.

I think some of the differences people find depends on how warm your house is, but you get more water loss in the winter, even from closed tanks.

We don't have our house as warm as a lot of people do, so we start off with a larger differential between tank and room temperature, which increases water loss.

There is also the differential in humidity between the air immediately above the water surface (fully saturated) and the humidity of the air in the room.

When cool, damp air comes into the house, via open windows and doors, it warms and the relative humidity falls. There is a really useful <"relative humidity calculator"> on the Lenntech web site.

I put 5oC and 100%RH as the outside temperature/humidity and 23oC as the internal temperature. The 100% saturated air coming in contains 5.74 g/kg of H2O, but by the time it has warmed up to 23oC it is only 33% saturated, and could potentially hold 17.6g/kg of H2O.

As soon as you get some temperature variation, or if you don't have good double glazing, that is a lot of condensation on the windows.

I monitored air humidty for a while about 3 cm above the water level.. In my case i was surprised how little it actualy was it never raised above 50% humidity.. It likely all comes back again to draft and ventialtion why it stays so low.. :)

cheers Darrel

I guess the biggest issue is the todays (re)building standard, everybody is pushed/subsidised to make a house as energy sufficient as possible. This means living in a sealed off as possible invironmet with a minimum of draft and thus a minimum of ventialtion. Than depending on the region lots of peoplle prefer it air conditioned and than we end up with the same story, air conditionng only works energy sufficient with a minimum of ventilation. Conditioning are is actualy recycling air in a sealed of invironment and refresh with x %/h. No wonder it needs filters. And no wonder lots of office workers in conditioned building spread a flew like wild fire.

If warm and moist air has no where to go than it can do only one thing and that is condense in the invironment on cool surfaces.

Than indeed having such a modern standardized draftless house, than open top tanks are not a good idea.

I'm lucky i live rented in a house dated from 1920 and even with double glazing and all closed in the winter it still drafts like crazy. I don't realy mind i have 3 open top tanks and never a single drop of condense water on the windows and everything is dry to the bone.. And with all 3 tanks i top off about 2 to 3 litres daily.

I monitored the air humidity for a while about 3 cm above the water level.. I actualy was surprised that it never raised over 50% during lights on.. It must come down again to draft and ventilation also from the warmth the lights above it produce a rising air column above the tank.. I have trouble to keep emersed mosses moist that are higher than 2 cm above the water surface.
 
Modern tight homes have worst indoor air quality. Toxic chemicals from building material, furniture and household chemicals can build up to levels that cause sick home syndrome. A remedy is to open windows slightly, vent heavily after returning home away for a few days, and don’t store toxic chemicals such as left over paint, paint thinner and other volatile organics inside the house.

My big tanks are all covered with glass top to prevent fish from jumping out, so evporation is reduced significantly but not eliminated. I never top them on purpose because I do large water change weekly anyway so tds and kH remain stable. One advantage of having a glass top is that it conserves CO2 I put in as the cover promotes redistribution and redissolving of escaped CO2 in the air space contained by the cover.

My shrimp bowls that I hanged by the window are open top, and I didn’t do any WC for months, just top with tap water as water evaporates away fast. The tds has gone up from 150 to 300, and kH from 4 to 7 in 6 months. I blamed on my shrimp gradual died off to lack of WC and mineral accumulation. Plants are supposed to reduce tds, kH and GH by taking up minerals but apparently my plant growth is too slow to catch up with the evaporation.
 
Last edited:
Over time topping up with tap water will increase TDS. However as stated above with weekly water changes or there abouts and extraction of minerals by plants there will be little impact on TDS. Do you still have very soft Brummy water. I used to live just outside Birmingham's water supply area and had liquid rock from South Staffs water. I use rain water its free, RO water is for the steam iron.

Thought about open top tanks but always concerned about fish jumping out and high room humidity from evaporation. Surprised by evaporational loses even from a closed tank.
No, I live about as far North as you can get and still be classed as Birmingham. My water is reasonably hard South Staffs water (GH12 / KH5) but I believe it also has a lot of farm run off so is pretty high in nitrates.

I get that plants will use some of what is in the water but surely, even with weekly 50% water changes, everything will constantly rise? Most people here seem to tear down their tanks every few years which probably means no issues but what about after 5/10 years?

Luckily (?) my house is old, damp and leaky but the heating is set to a balmy 19°C when we are in and is setup to not let things drop below 14°C (which was only as a result of having a tank heater fail on me)
 
After reading my response do you understand what I'm saying?
I usually do a WC every 7 days which is my aim but sometimes more often and sometimes it will slip to day 8 or 9 but that's unfortunately out of my contr

After reading your initial post, no, but after reading this one yes.

I get that plants will use some of what is in the water but surely, even with weekly 50% water changes, everything will constantly rise? Most people here seem to tear down their tanks every few years which probably means no issues but what about after 5/10 years?

TDS meter is handy to keep the tank measure in close range to the tap measure. Sufficient water changes will help with that and the tank can run "healthy" theoretically forever,open or closed.

And no wonder lots of office workers in conditioned building spread a flew like wild fire.

Through the air conditioning vents at work I can smell what they cook in the canteen, when they've used chemicals somewhere to clean, and it all blows right in my face...In my previous job I sat right under a very dirty grill and I used to get sick every two months. I was saying to a friend recently that there will be time when air conditioning and closed environment such as the current offices will be ruled illegal one day....

When cool, damp air comes into the house, via open windows and doors, it warms and the relative humidity falls. There is a really useful <"relative humidity calculator"> on the Lenntech web site.

I keep my fish room window slightly open at all times. In the summer wide open. It helps with the humidity although its not energy efficient. I also like having a bit of fresh air.
 
Hi all,
I keep my fish room window slightly open at all times. In the summer wide open. It helps with the humidity although its not energy efficient. I also like having a bit of fresh air.
We do the same, I can't remember the exact figure (half a litre?) but each human in a house breathes out quite a lot of water vapour every day even without the contribution of plants and fish-tanks.

cheers Darrel
 
I guess condensation etc aside the most important question is, how does it affect our health?
My tank is in the study and if the door has been closed for a while the moisture in the air is palpable.
 
Air humidity between 70-90% is afaik deemed most healthy invironment.. Pretty difficult to reach this as a constant without condensation.
Condensation as we know by itself is distilled water, nothing unhealthy about that. It is no ventilation and what stays with it is the killer in the end..
 
Back
Top