## 5 Summary and Conclusions  
The study employed an incubation experiment in natural lake water to compare the performance of two solutions, laminates and modules, developed for non-invasive Premoval from aquatic ecosystems. Both techniques enable reductions in the OP availability in the lake water and its removal from the ecosystem without the permanent deposition of the P binding agent in water bodies. Both treatments, using laminates and modules, lowered the OP concentration in the lake water for at least 6 weeks (42 days) compared to no treatment, but the performance of modules was much higher. They effectively eliminated the OP initially available in the system (present in the lake water) and further captured the OP newly supplied by the decomposition processes, showing continuous OP uptake, while laminates appeared to exhaust their fixation capacity after about 1 week. Both solutions caused only a slight pH decrease compared to the control treatment, with a minor change of up to 0.2 points. The distinctly higher efficiency and longevity of modules compared to laminates results mostly from technical design as much larger calcite mass can be applied on a carrier when using modules (the calcite dose per m\({}^{2}\) of the surface area is 168 times higher in modules compared to laminates (4050 vs. 24 g)). To achieve a long-lasting effect (weeks, months) without the need to exchange the carriers, modules represent a more advisable solution compared to laminates. Therefore, modules have the most potential for the implementation in practice as they are able to decrease the OP concentration for relatively long time periods of weeks to months without the need to be exchanged. What is more, they offer a refillable and reusable system for P control, removal, and recovery. As modules need at least few weeks to substantially reduce the OP concentration, their application is mostly advisable before start of the vegetation season (or expected intense primary production of phytoplankton) and/or below the euphotic zone. In the future, field tests at a semi-technical scale should be performed to verify the performance of modules and laminates under actual in-lake conditions and complex interactions with the aquatic organisms to check for possible limitations and/or synergies between non-invasive P removal techniques and native processes. Long-term (months) treatment should be employed to check for the maximum longevity of OP removal that can be gained. Further research is needed on the reuse of the binding agent and P recycling, particularly regarding the separation of reactive materials from laminates and modules, as well as the potential for P recovery or direct reuse of the P-loaded binding agent, for instance as a soil amendment. Conceptualization, A.B.-S., D.B., D.P.-F. and G.B. ; data curation, A.B.-S., D.B. and D.P.-F.; formal analysis, A.B.-S., D.B. and D.P.-F.; funding acquisition, A.B.-S., D.B., D.P.-F. and G.B. ; investigation, A.B.-S., D.P.-F., J.I., L.K. and W.L. ; methodology, A.B.-S., D.B. and D.P.-F.; project administration, D.B. and G.B. ; resources, A.B.-S., D.B., D.P.-F. and G.B. ; supervision, D.B. and G.B. ; validation, A.B.-S., D.B. and D.P.-F.; visualization, A.B.-S., D.B. and D.P.-F.; writing--original draft, A.B.-S. and D.B. ; writing--review and editing, A.B.-S., D.B., D.P.-F., J.I., L.K., W.L. and G.B. All authors have read and agreed to the published version of the manuscript. This project was funded by the European Union and Republic of Poland within the Smart Growth Operational Program 2014-2020, Priority axis I: Support for R&D activity of enterprises, R&D projects of enterprises, industrial research and development works (grant number POIR.01.01.01-00-0981/17-00). Not applicable. Data availability Statement: Data will be made available on request. Acknowledgments: [PERSON] (APRS) is greatly acknowledged for his technical engagement in constructing the prototype of modules. Conflicts of Interest: Authors [PERSON] and [PERSON] were employed by the company APRS.