ROMA 125 - Removing the lid?

[JBFUK]

I have a Roma 125, it has 2x 32W Fluval Plant 3.0 LED lights. While doing water changes, pruning etc, I noticed that with the lid off and lights sitting astride the top rim I get significantly better light coverage inside the tank. I'm thinking of leaving the lid off and lights up there for a week or two so that I can see how the plants respond - particularly the ones in the darker corners. It could also be beneficial for the floating plants to have a bit more airflow.

Is there anything I should be aware of when looking to leave the top off? Issues with water temp changes, problems in the room with humidity and condensation, the need to top off the water often etc etc?

 

[heliophyte]

You will have more evaporation, also some fish are prone to jumping, especially those that like to stay in the top regions of the tank normally.

 

[JBFUK]

Thanks, I'll give it a go for a few days. I'd read that black phantoms can be prone to jumping and I have around 6 of them, however they rarely go near the top levels of the tank and I have a reasonably good covering of floating plants.

When you top off the water is it important to use RO? I've read in some places that topping off with (hard) tap water can lead to the tanks TDS and GH gradually getting higher and higher due to the water evaporating but not the minerals, which build up over time.

 

[arcturus]

Thanks, I'll give it a go for a few days. I'd read that black phantoms can be prone to jumping and I have around 6 of them, however they rarely go near the top levels of the tank and I have a reasonably good covering of floating plants.

Floating plants do help. You can also lower the water level a couple of cms. If you have problematic fish or shrimp you can add a mesh to the top of the tank, but it can be a bit unsightly.

When you top off the water is it important to use RO? I've read in some places that topping off with (hard) tap water can lead to the tanks TDS and GH gradually getting higher and higher due to the water evaporating but not the minerals, which build up over time.

No need to use RO. Just keep up with regular water changes. This is sufficient to remove and dilute the compounds in the water. Be sure to use dechlorinated water when you top off - you can keep a small tank of water ready. You might need a few litres per week, depending on the evaporation rate.

Is there anything I should be aware of when looking to leave the top off? Issues with water temp changes, problems in the room with humidity and condensation, the need to top off the water often etc etc?

Temperature should drop a bit. But this is actually good thing because most tanks can be kept at near room temp. The change in humidity will be minor and during the colder months you will have a low relative humidity due to heating anyway. Just be sure you do not have wooden shelves or other furniture immediately above the open tank. Otherwise no need to worry about that.

 

[JBFUK]

I don't know whether it's just my imagination but the fish seem a lot happier and more active. Perhaps they're getting more oxygen with the improved airflow.

 

[arcturus]

I don't know whether it's just my imagination but the fish seem a lot happier and more active. Perhaps they're getting more oxygen with the improved airflow.

That is a possibility. Gaseous exchange can be more limited in tanks with a lid. For example, CO2 may not reset to atmospheric levels during the night in a closed tank, but will get to a lower level if you keep the lid open. And a lot of floating plants struggle in closed tanks, but that is a result of higher humidity, condensation, temperature, etc. and not only access to CO2 and O2. Another possibility is the slightly reduced light intensity due to raising the lights, since most fish do not light strong lights.